Method and apparatus for compression-based csi reporting

ABSTRACT

A method for operating a user equipment (UE) comprises receiving a configuration about a CSI report, the configuration including information about a codebook, the codebook comprising components: (i) sets of basis vectors including a first set of vectors each of length P CSIRS ×1 for a SD, a second set of vectors each of length N 3 ×1 for a FD, and a third set of vectors each of length N 4 ×1 for a DD, and (ii) coefficients associated with each basis vector triple (a i ,b f ,c d ), a i  from the first set, b f  from the second set, and c d  from the third set; determining, based on the configuration, the components; and transmitting the CSI report including: at least one basis vector indicator indicating all or a portion of the sets of basis vectors, and at least one coefficient indicator indicating all or a portion of the coefficients.

CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY

The present application claims priority to U.S. Provisional PatentApplication No. 63/225,234, filed on Jul. 23, 2021, U.S. ProvisionalPatent Application No. 63/335,557, filed on Apr. 27, 2022, and U.S.Provisional Patent Application No. 63/341,382, filed on May 12, 2022.The content of the above-identified patent document is incorporatedherein by reference.

TECHNICAL FIELD

The present disclosure relates generally to wireless communicationsystems and more specifically to compression-based CSI reporting.

BACKGROUND

Understanding and correctly estimating the channel between a userequipment (UE) and a base station (BS) (e.g., gNode B (gNB)) isimportant for efficient and effective wireless communication. In orderto correctly estimate the DL channel conditions, the gNB may transmit areference signal, e.g., CSI-RS, to the UE for DL channel measurement,and the UE may report (e.g., feedback) information about channelmeasurement, e.g., CSI, to the gNB. With this DL channel measurement,the gNB is able to select appropriate communication parameters toefficiently and effectively perform wireless data communication with theUE.

SUMMARY

Embodiments of the present disclosure provide methods and apparatusesfor signaling on CSI format.

In one embodiment, a UE in a wireless communication system is provided.The UE includes a transceiver configured to: receive a configurationabout a channel state information (CSI) report, the configurationincluding information about a codebook, the codebook comprisingcomponents: (i) sets of basis vectors including a first set of vectorseach of length P_(CSIRS)×1 for a spatial domain (SD), a second set ofvectors each of length N₃×1 for a frequency domain (FD), and a third setof vectors each of length N₄×1 for a Doppler domain (DD), and (ii)coefficients associated with each basis vector triple(a_(i),b_(f),c_(d)), a_(t) from the first set, b_(f) from the secondset, and c_(d) from the third set. The UE further includes a processoroperably coupled to the transceiver. The processor is configured to:determine, based on the configuration, the components. The transceiveris further configured to transmit the CSI report including: at least onebasis vector indicator indicating all or a portion of the sets of basisvectors, and at least one coefficient indicator indicating all or aportion of the coefficients, wherein N₃ and N₄ are total number of FDand DD units respectively, and wherein P_(CSIRS) is a number of CSI-RSports configured for the CSI report.

In another embodiment, a BS in a wireless communication system isprovided. The BS includes a processor configured to: generate aconfiguration about a CSI report, the configuration includinginformation about a codebook, the codebook comprising components: (i)sets of basis vectors including a first set of vectors each of lengthP_(CSIRS)×1 for a SD, a second set of vectors each of length N₃×1 for aFD, and a third set of vectors each of length N₄×1 for a DD, and (ii)coefficients associated with each basis vector triple(a_(i),b_(f),c_(d)), a_(t) from the first set, b_(f) from the secondset, and c_(d) from the third set. The BS further includes a transceiveroperably coupled to the processor. The transceiver is configured to:transmit the configuration; and receive the CSI report based on theconfiguration, wherein the CSI report includes: at least one basisvector indicator indicating all or a portion of the sets of basisvectors, and at least one coefficient indicator indicating all or aportion of the coefficients, wherein N₃ and N₄ are total number of FDand DD units respectively, and wherein P_(CSIRS) is a number of CSI-RSports configured for the CSI report.

In yet another embodiment, a method for operating a UE is provided. Themethod comprises: receiving a configuration about a CSI report, theconfiguration including information about a codebook, the codebookcomprising components: (i) sets of basis vectors including a first setof vectors each of length P_(CSIRS)×1 for a SD, a second set of vectorseach of length N₃×1 for a FD, and a third set of vectors each of lengthN₄×1 for a DD, and (ii) coefficients associated with each basis vectortriple (a_(i),b_(f),c_(d)), a_(t) from the first set, b_(f) from thesecond set, and c_(d) from the third set; determining, based on theconfiguration, the components; and transmitting the CSI reportincluding: at least one basis vector indicator indicating all or aportion of the sets of basis vectors, and at least one coefficientindicator indicating all or a portion of the coefficients, wherein N₃and N₄ are total number of FD and DD units respectively, and whereinP_(CSIRS) is a number of CSI-RS ports configured for the CSI report.

Other technical features may be readily apparent to one skilled in theart from the following figures, descriptions, and claims.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document. The term “couple” and its derivativesrefer to any direct or indirect communication between two or moreelements, whether or not those elements are in physical contact with oneanother. The terms “transmit,” “receive,” and “communicate,” as well asderivatives thereof, encompass both direct and indirect communication.The terms “include” and “comprise,” as well as derivatives thereof, meaninclusion without limitation. The term “or” is inclusive, meaningand/or. The phrase “associated with,” as well as derivatives thereof,means to include, be included within, interconnect with, contain, becontained within, connect to or with, couple to or with, be communicablewith, cooperate with, interleave, juxtapose, be proximate to, be boundto or with, have, have a property of, have a relationship to or with, orthe like. The term “controller” means any device, system or part thereofthat controls at least one operation. Such a controller may beimplemented in hardware or a combination of hardware and software and/orfirmware. The functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely. Thephrase “at least one of,” when used with a list of items, means thatdifferent combinations of one or more of the listed items may be used,and only one item in the list may be needed. For example, “at least oneof: A, B, and C” includes any of the following combinations: A, B, C, Aand B, A and C, B and C, and A and B and C.

Moreover, various functions described below can be implemented orsupported by one or more computer programs, each of which is formed fromcomputer readable program code and embodied in a computer readablemedium. The terms “application” and “program” refer to one or morecomputer programs, software components, sets of instructions,procedures, functions, objects, classes, instances, related data, or aportion thereof adapted for implementation in a suitable computerreadable program code. The phrase “computer readable program code”includes any type of computer code, including source code, object code,and executable code. The phrase “computer readable medium” includes anytype of medium capable of being accessed by a computer, such as readonly memory (ROM), random access memory (RAM), a hard disk drive, acompact disc (CD), a digital video disc (DVD), or any other type ofmemory. A “non-transitory” computer readable medium excludes wired,wireless, optical, or other communication links that transporttransitory electrical or other signals. A non-transitory computerreadable medium includes media where data can be permanently stored andmedia where data can be stored and later overwritten, such as arewritable optical disc or an erasable memory device.

Definitions for other certain words and phrases are provided throughoutthis patent document. Those of ordinary skill in the art shouldunderstand that in many if not most instances, such definitions apply toprior as well as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 illustrates an example wireless network according to embodimentsof the present disclosure;

FIG. 2 illustrates an example gNB according to embodiments of thepresent disclosure;

FIG. 3 illustrates an example UE according to embodiments of the presentdisclosure;

FIG. 4A illustrates a high-level diagram of an orthogonal frequencydivision multiple access transmit path according to embodiments of thepresent disclosure;

FIG. 4B illustrates a high-level diagram of an orthogonal frequencydivision multiple access receive path according to embodiments of thepresent disclosure;

FIG. 5 illustrates a transmitter block diagram for a PDSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 6 illustrates a receiver block diagram for a PDSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 7 illustrates a transmitter block diagram for a PUSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 8 illustrates a receiver block diagram for a PUSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 9 illustrates an example antenna blocks or arrays forming beamsaccording to embodiments of the present disclosure;

FIG. 10 illustrates channel measurements with and without Dopplercomponents according to embodiments of the present disclosure;

FIG. 11 illustrates an antenna port layout according to embodiments ofthe present disclosure;

FIG. 12 illustrates a 3D grid of oversampled DFT beams according toembodiments of the present disclosure;

FIG. 13 illustrates an example of a UE configured to receive a burst ofNZP CSI-RS resources according to embodiments of the present disclosure;

FIG. 14 illustrates an example of a UE configured to determine a valueof N₄ based on the value B in a CSI-RS burst and a sub-time unit sizeN_(ST) according to embodiments of the present disclosure;

FIG. 15 illustrates an example of a UE configured to determine a valueof frequency-domain unit and a value of time/Doppler domain unit basedon j≥1 CSI-RS bursts that occupy a frequency band and a time spanaccording to embodiments of the present disclosure;

FIG. 16 illustrates a flow chart of a method for operating a UEaccording to embodiments of the present disclosure; and

FIG. 17 illustrates a flow chart of a method for operating a BSaccording to embodiments of the present disclosure.

DETAILED DESCRIPTION

FIG. 1 through FIG. 17 , discussed below, and the various embodimentsused to describe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged system or device.

The following documents and standards descriptions are herebyincorporated by reference into the present disclosure as if fully setforth herein: 3GPP TS 36.211 v17.0.0, “E-UTRA, Physical channels andmodulation” (herein “REF 1”); 3GPP TS 36.212 v17.0.0, “E-UTRA,Multiplexing and Channel coding” (herein “REF 2”); 3GPP TS 36.213v17.0.0, “E-UTRA, Physical Layer Procedures” (herein “REF 3”); 3GPP TS36.321 v16.6.0, “E-UTRA, Medium Access Control (MAC) protocolspecification” (herein “REF 4”); 3GPP TS 36.331 v16.7.0, “E-UTRA, RadioResource Control (RRC) protocol specification” (herein “REF 5”); 3GPP TR22.891 v1.2.0 (herein “REF 6”); 3GPP TS 38.212 v17.0.0, “E-UTRA, NR,Multiplexing and channel coding” (herein “REF 7”); 3GPP TS 38.214v17.0.0, “E-UTRA, NR, Physical layer procedures for data” (herein “REF8”); RP-192978, “Measurement results on Doppler spectrum for various UEmobility environments and related CSI enhancements,” Fraunhofer IIS,Fraunhofer HHI, Deutsche Telekom (herein “REF 9”); and 3GPP TS 38.211v17.0.0, “E-UTRA, NR, Physical channels and modulation (herein “REF10”).

Aspects, features, and advantages of the disclosure are readily apparentfrom the following detailed description, simply by illustrating a numberof particular embodiments and implementations, including the best modecontemplated for carrying out the disclosure. The disclosure is alsocapable of other and different embodiments, and its several details canbe modified in various obvious respects, all without departing from thespirit and scope of the disclosure. Accordingly, the drawings anddescription are to be regarded as illustrative in nature, and not asrestrictive. The disclosure is illustrated by way of example, and not byway of limitation, in the figures of the accompanying drawings.

In the following, for brevity, both FDD and TDD are considered as theduplex method for both DL and UL signaling.

Although exemplary descriptions and embodiments to follow assumeorthogonal frequency division multiplexing (OFDM) or orthogonalfrequency division multiple access (OFDMA), the present disclosure canbe extended to other OFDM-based transmission waveforms or multipleaccess schemes such as filtered OFDM (F-OFDM).

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a “beyond 4G network” or a“post LTE system.”

The 5G communication system is considered to be implemented in higherfrequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higherdata rates or in lower frequency bands, such as below 6 GHz, to enablerobust coverage and mobility support. To decrease propagation loss ofthe radio waves and increase the transmission coverage, the beamforming,massive multiple-input multiple-output (MIMO), full dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques and the like are discussed in 5G communication systems.

In addition, in 5G communication systems, development for system networkimprovement is under way based on advanced small cells, cloud radioaccess networks (RANs), ultra-dense networks, device-to-device (D2D)communication, wireless backhaul communication, moving network,cooperative communication, coordinated multi-points (CoMP) transmissionand reception, interference mitigation and cancelation and the like.

The discussion of 5G systems and frequency bands associated therewith isfor reference as certain embodiments of the present disclosure may beimplemented in 5G systems. However, the present disclosure is notlimited to 5G systems, or the frequency bands associated therewith, andembodiments of the present disclosure may be utilized in connection withany frequency band. For example, aspects of the present disclosure mayalso be applied to deployment of 5G communication systems, 6G or evenlater releases which may use terahertz (THz) bands.

FIGS. 1-4B below describe various embodiments implemented in wirelesscommunications systems and with the use of orthogonal frequency divisionmultiplexing (OFDM) or orthogonal frequency division multiple access(OFDMA) communication techniques. The descriptions of FIGS. 1-3 are notmeant to imply physical or architectural limitations to the manner inwhich different embodiments may be implemented. Different embodiments ofthe present disclosure may be implemented in any suitably-arrangedcommunications system. The present disclosure covers several componentswhich can be used in conjunction or in combination with one another orcan operate as standalone schemes.

FIG. 1 illustrates an example wireless network according to embodimentsof the present disclosure. The embodiment of the wireless network shownin FIG. 1 is for illustration only. Other embodiments of the wirelessnetwork 100 could be used without departing from the scope of thisdisclosure.

As shown in FIG. 1 , the wireless network includes a gNB 101, a gNB 102,and a gNB 103. The gNB 101 communicates with the gNB 102 and the gNB103. The gNB 101 also communicates with at least one network 130, suchas the Internet, a proprietary Internet Protocol (IP) network, or otherdata network.

The gNB 102 provides wireless broadband access to the network 130 for afirst plurality of user equipments (UEs) within a coverage area 120 ofthe gNB 102. The first plurality of UEs includes a UE 111, which may belocated in a small business; a UE 112, which may be located in anenterprise (E); a UE 113, which may be located in a WiFi hotspot (HS); aUE 114, which may be located in a first residence (R); a UE 115, whichmay be located in a second residence (R); and a UE 116, which may be amobile device (M), such as a cell phone, a wireless laptop, a wirelessPDA, or the like. The gNB 103 provides wireless broadband access to thenetwork 130 for a second plurality of UEs within a coverage area 125 ofthe gNB 103. The second plurality of UEs includes the UE 115 and the UE116. In some embodiments, one or more of the gNBs 101-103 maycommunicate with each other and with the UEs 111-116 using 5G, LTE,LTE-A, WiMAX, WiFi, or other wireless communication techniques.

Depending on the network type, the term “base station” or “BS” can referto any component (or collection of components) configured to providewireless access to a network, such as transmit point (TP),transmit-receive point (TRP), an enhanced base station (eNodeB or eNB),a 5G base station (gNB), a macrocell, a femtocell, a WiFi access point(AP), or other wirelessly enabled devices. Base stations may providewireless access in accordance with one or more wireless communicationprotocols, e.g., 5G 3GPP new radio interface/access (NR), long termevolution (LTE), LTE advanced (LTE-A), high speed packet access (HSPA),Wi-Fi 802.11a/b/g/n/ac, etc. For the sake of convenience, the terms “BS”and “TRP” are used interchangeably in this patent document to refer tonetwork infrastructure components that provide wireless access to remoteterminals. Also, depending on the network type, the term “userequipment” or “UE” can refer to any component such as “mobile station,”“subscriber station,” “remote terminal,” “wireless terminal,” “receivepoint,” or “user device.” For the sake of convenience, the terms “userequipment” and “UE” are used in this patent document to refer to remotewireless equipment that wirelessly accesses a BS, whether the UE is amobile device (such as a mobile telephone or smartphone) or is normallyconsidered a stationary device (such as a desktop computer or vendingmachine).

Dotted lines show the approximate extents of the coverage areas 120 and125, which are shown as approximately circular for the purposes ofillustration and explanation only. It should be clearly understood thatthe coverage areas associated with gNBs, such as the coverage areas 120and 125, may have other shapes, including irregular shapes, dependingupon the configuration of the gNBs and variations in the radioenvironment associated with natural and man-made obstructions.

As described in more detail below, one or more of the UEs 111-116include circuitry, programing, or a combination thereof, for receiving aconfiguration about a CSI report, the configuration includinginformation about a codebook, the codebook comprising components: (i)sets of basis vectors including a first set of vectors each of lengthP_(CSIRS)×1 for a SD, a second set of vectors each of length N₃×1 for aFD, and a third set of vectors each of length N₄×1 for a DD, and (ii)coefficients associated with each basis vector triple(a_(i),b_(f),c_(d)), a_(t) from the first set, b_(f) from the secondset, and c_(d) from the third set; determining, based on theconfiguration, the components; and transmitting the CSI reportincluding: at least one basis vector indicator indicating all or aportion of the sets of basis vectors, and at least one coefficientindicator indicating all or a portion of the coefficients, wherein N₃and N₄ are total number of FD and DD units respectively, and whereinP_(CSIRS) is a number of CSI-RS ports configured for the CSI report. Oneor more of the gNBs 101-103 includes circuitry, programing, or acombination thereof, for generating a configuration about a CSI report,the configuration including information about a codebook, the codebookcomprising components: (i) sets of basis vectors including a first setof vectors each of length P_(CSIRS)×1 for a SD, a second set of vectorseach of length N₃×1 for a FD, and a third set of vectors each of lengthN₄×1 for a DD, and (ii) coefficients associated with each basis vectortriple (a_(i),b_(f),c_(d)), a_(t) from the first set, b_(f) from thesecond set, and c_(d) from the third set; transmitting theconfiguration; and receiving the CSI report based on the configuration,wherein the CSI report includes: at least one basis vector indicatorindicating all or a portion of the sets of basis vectors, and at leastone coefficient indicator indicating all or a portion of thecoefficients, wherein N₃ and N₄ are total number of FD and DD unitsrespectively, and wherein P_(CSIRS) is a number of CSI-RS portsconfigured for the CSI report.

Although FIG. 1 illustrates one example of a wireless network, variouschanges may be made to FIG. 1 . For example, the wireless network couldinclude any number of gNBs and any number of UEs in any suitablearrangement. Also, the gNB 101 could communicate directly with anynumber of UEs and provide those UEs with wireless broadband access tothe network 130. Similarly, each gNB 102-103 could communicate directlywith the network 130 and provide UEs with direct wireless broadbandaccess to the network 130. Further, the gNBs 101, 102, and/or 103 couldprovide access to other or additional external networks, such asexternal telephone networks or other types of data networks.

FIG. 2 illustrates an example gNB 102 according to embodiments of thepresent disclosure. The embodiment of the gNB 102 illustrated in FIG. 2is for illustration only, and the gNBs 101 and 103 of FIG. 1 could havethe same or similar configuration. However, gNBs come in a wide varietyof configurations, and FIG. 2 does not limit the scope of thisdisclosure to any particular implementation of a gNB.

As shown in FIG. 2 , the gNB 102 includes multiple antennas 205 a-205 n,multiple RF transceivers 210 a-210 n, transmit (TX) processing circuitry215, and receive (RX) processing circuitry 220. The gNB 102 alsoincludes a controller/processor 225, a memory 230, and a backhaul ornetwork interface 235.

The RF transceivers 210 a-210 n receive, from the antennas 205 a-205 n,incoming RF signals, such as signals transmitted by UEs in the network100. The RF transceivers 210 a-210 n down-convert the incoming RFsignals to generate IF or baseband signals. The IF or baseband signalsare sent to the RX processing circuitry 220, which generates processedbaseband signals by filtering, decoding, and/or digitizing the basebandor IF signals. The RX processing circuitry 220 transmits the processedbaseband signals to the controller/processor 225 for further processing.

The TX processing circuitry 215 receives analog or digital data (such asvoice data, web data, e-mail, or interactive video game data) from thecontroller/processor 225. The TX processing circuitry 215 encodes,multiplexes, and/or digitizes the outgoing baseband data to generateprocessed baseband or IF signals. The RF transceivers 210 a-210 nreceive the outgoing processed baseband or IF signals from the TXprocessing circuitry 215 and up-converts the baseband or IF signals toRF signals that are transmitted via the antennas 205 a-205 n.

The controller/processor 225 can include one or more processors or otherprocessing devices that control the overall operation of the gNB 102.For example, the controller/processor 225 could control the reception ofUL channel signals and the transmission of DL channel signals by the RFtransceivers 210 a-210 n, the RX processing circuitry 220, and the TXprocessing circuitry 215 in accordance with well-known principles. Thecontroller/processor 225 could support additional functions as well,such as more advanced wireless communication functions.

For instance, the controller/processor 225 could support beam forming ordirectional routing operations in which outgoing signals from multipleantennas 205 a-205 n are weighted differently to effectively steer theoutgoing signals in a desired direction. Any of a wide variety of otherfunctions could be supported in the gNB 102 by the controller/processor225.

The controller/processor 225 is also capable of executing programs andother processes resident in the memory 230, such as an OS. Thecontroller/processor 225 can move data into or out of the memory 230 asrequired by an executing process.

The controller/processor 225 is also coupled to the backhaul or networkinterface 235. The backhaul or network interface 235 allows the gNB 102to communicate with other devices or systems over a backhaul connectionor over a network. The interface 235 could support communications overany suitable wired or wireless connection(s). For example, when the gNB102 is implemented as part of a cellular communication system (such asone supporting 5G, LTE, or LTE-A), the interface 235 could allow the gNB102 to communicate with other gNBs over a wired or wireless backhaulconnection. When the gNB 102 is implemented as an access point, theinterface 235 could allow the gNB 102 to communicate over a wired orwireless local area network or over a wired or wireless connection to alarger network (such as the Internet). The interface 235 includes anysuitable structure supporting communications over a wired or wirelessconnection, such as an Ethernet or RF transceiver.

The memory 230 is coupled to the controller/processor 225. Part of thememory 230 could include a RAM, and another part of the memory 230 couldinclude a Flash memory or other ROM.

Although FIG. 2 illustrates one example of gNB 102, various changes maybe made to FIG. 2 . For example, the gNB 102 could include any number ofeach component shown in FIG. 2 . As a particular example, an accesspoint could include a number of interfaces 235, and thecontroller/processor 225 could support routing functions to route databetween different network addresses. As another particular example,while shown as including a single instance of TX processing circuitry215 and a single instance of RX processing circuitry 220, the gNB 102could include multiple instances of each (such as one per RFtransceiver). Also, various components in FIG. 2 could be combined,further subdivided, or omitted and additional components could be addedaccording to particular needs.

FIG. 3 illustrates an example UE 116 according to embodiments of thepresent disclosure. The embodiment of the UE 116 illustrated in FIG. 3is for illustration only, and the UEs 111-115 of FIG. 1 could have thesame or similar configuration. However, UEs come in a wide variety ofconfigurations, and FIG. 3 does not limit the scope of this disclosureto any particular implementation of a UE.

As shown in FIG. 3 , the UE 116 includes an antenna 305, a radiofrequency (RF) transceiver 310, TX processing circuitry 315, amicrophone 320, and receive (RX) processing circuitry 325. The UE 116also includes a speaker 330, a processor 340, an input/output (I/O)interface (IF) 345, a touchscreen 350, a display 355, and a memory 360.The memory 360 includes an operating system (OS) 361 and one or moreapplications 362.

The RF transceiver 310 receives, from the antenna 305, an incoming RFsignal transmitted by a gNB of the network 100. The RF transceiver 310down-converts the incoming RF signal to generate an intermediatefrequency (IF) or baseband signal. The IF or baseband signal is sent tothe RX processing circuitry 325, which generates a processed basebandsignal by filtering, decoding, and/or digitizing the baseband or IFsignal. The RX processing circuitry 325 transmits the processed basebandsignal to the speaker 330 (such as for voice data) or to the processor340 for further processing (such as for web browsing data).

The TX processing circuitry 315 receives analog or digital voice datafrom the microphone 320 or other outgoing baseband data (such as webdata, e-mail, or interactive video game data) from the processor 340.The TX processing circuitry 315 encodes, multiplexes, and/or digitizesthe outgoing baseband data to generate a processed baseband or IFsignal. The RF transceiver 310 receives the outgoing processed basebandor IF signal from the TX processing circuitry 315 and up-converts thebaseband or IF signal to an RF signal that is transmitted via theantenna 305.

The processor 340 can include one or more processors or other processingdevices and execute the OS 361 stored in the memory 360 in order tocontrol the overall operation of the UE 116. For example, the processor340 could control the reception of DL channel signals and thetransmission of UL channel signals by the RF transceiver 310, the RXprocessing circuitry 325, and the TX processing circuitry 315 inaccordance with well-known principles. In some embodiments, theprocessor 340 includes at least one microprocessor or microcontroller.

The processor 340 is also capable of executing other processes andprograms resident in the memory 360, such as processes for receiving aconfiguration about a CSI report, the configuration includinginformation about a codebook, the codebook comprising components: (i)sets of basis vectors including a first set of vectors each of lengthP_(CSIRS)×1 for a SD, a second set of vectors each of length N₃×1 for aFD, and a third set of vectors each of length N₄×1 for a DD, and (ii)coefficients associated with each basis vector triple(a_(i),b_(f),c_(d)), a_(t) from the first set, b_(f) from the secondset, and c_(d) from the third set; determining, based on theconfiguration, the components; and transmitting the CSI reportincluding: at least one basis vector indicator indicating all or aportion of the sets of basis vectors, and at least one coefficientindicator indicating all or a portion of the coefficients, wherein N₃and N₄ are total number of FD and DD units respectively, and whereinP_(CSIRS) is a number of CSI-RS ports configured for the CSI report. Theprocessor 340 can move data into or out of the memory 360 as required byan executing process. In some embodiments, the processor 340 isconfigured to execute the applications 362 based on the OS 361 or inresponse to signals received from gNBs or an operator. The processor 340is also coupled to the I/O interface 345, which provides the UE 116 withthe ability to connect to other devices, such as laptop computers andhandheld computers. The I/O interface 345 is the communication pathbetween these accessories and the processor 340.

The processor 340 is also coupled to the touchscreen 350 and the display355. The operator of the UE 116 can use the touchscreen 350 to enterdata into the UE 116. The display 355 may be a liquid crystal display,light emitting diode display, or other display capable of rendering textand/or at least limited graphics, such as from web sites.

The memory 360 is coupled to the processor 340. Part of the memory 360could include a random-access memory (RAM), and another part of thememory 360 could include a Flash memory or other read-only memory (ROM).

Although FIG. 3 illustrates one example of UE 116, various changes maybe made to FIG. 3 . For example, various components in FIG. 3 could becombined, further subdivided, or omitted and additional components couldbe added according to particular needs. As a particular example, theprocessor 340 could be divided into multiple processors, such as one ormore central processing units (CPUs) and one or more graphics processingunits (GPUs). Also, while FIG. 3 illustrates the UE 116 configured as amobile telephone or smartphone, UEs could be configured to operate asother types of mobile or stationary devices.

FIG. 4A is a high-level diagram of transmit path circuitry. For example,the transmit path circuitry may be used for an orthogonal frequencydivision multiple access (OFDMA) communication. FIG. 4B is a high-leveldiagram of receive path circuitry. For example, the receive pathcircuitry may be used for an orthogonal frequency division multipleaccess (OFDMA) communication. In FIGS. 4A and 4B, for downlinkcommunication, the transmit path circuitry may be implemented in a basestation (gNB) 102 or a relay station, and the receive path circuitry maybe implemented in a user equipment (e.g., user equipment 116 of FIG. 1). In other examples, for uplink communication, the receive pathcircuitry 450 may be implemented in a base station (e.g., gNB 102 ofFIG. 1 ) or a relay station, and the transmit path circuitry may beimplemented in a user equipment (e.g., user equipment 116 of FIG. 1 ).

Transmit path circuitry comprises channel coding and modulation block405, serial-to-parallel (S-to-P) block 410, Size N Inverse Fast FourierTransform (IFFT) block 415, parallel-to-serial (P-to-S) block 420, addcyclic prefix block 425, and up-converter (UC) 430. Receive pathcircuitry 450 comprises down-converter (DC) 455, remove cyclic prefixblock 460, serial-to-parallel (S-to-P) block 465, Size N Fast FourierTransform (FFT) block 470, parallel-to-serial (P-to-S) block 475, andchannel decoding and demodulation block 480.

At least some of the components in FIGS. 4A 400 and 4B 450 may beimplemented in software, while other components may be implemented byconfigurable hardware or a mixture of software and configurablehardware. In particular, it is noted that the FFT blocks and the IFFTblocks described in this disclosure document may be implemented asconfigurable software algorithms, where the value of Size N may bemodified according to the implementation.

Furthermore, although this disclosure is directed to an embodiment thatimplements the Fast Fourier Transform and the Inverse Fast FourierTransform, this is by way of illustration only and may not be construedto limit the scope of the disclosure. It may be appreciated that in analternate embodiment of the present disclosure, the Fast FourierTransform functions and the Inverse Fast Fourier Transform functions mayeasily be replaced by discrete Fourier transform (DFT) functions andinverse discrete Fourier transform (IDFT) functions, respectively. Itmay be appreciated that for DFT and IDFT functions, the value of the Nvariable may be any integer number (i.e., 1, 4, 3, 4, etc.), while forFFT and IFFT functions, the value of the N variable may be any integernumber that is a power of two (i.e., 1, 2, 4, 8, 16, etc.).

In transmit path circuitry 400, channel coding and modulation block 405receives a set of information bits, applies coding (e.g., LDPC coding)and modulates (e.g., quadrature phase shift keying (QPSK) or quadratureamplitude modulation (QAM)) the input bits to produce a sequence offrequency-domain modulation symbols. Serial-to-parallel block 410converts (i.e., de-multiplexes) the serial modulated symbols to paralleldata to produce N parallel symbol streams where N is the IFFT/FFT sizeused in BS 102 and UE 116. Size N IFFT block 415 then performs an IFFToperation on the N parallel symbol streams to produce time-domain outputsignals. Parallel-to-serial block 420 converts (i.e., multiplexes) theparallel time-domain output symbols from Size N IFFT block 415 toproduce a serial time-domain signal. Add cyclic prefix block 425 theninserts a cyclic prefix to the time-domain signal. Finally, up-converter430 modulates (i.e., up-converts) the output of add cyclic prefix block425 to RF frequency for transmission via a wireless channel. The signalmay also be filtered at baseband before conversion to RF frequency.

The transmitted RF signal arrives at the UE 116 after passing throughthe wireless channel, and reverse operations to those at gNB 102 areperformed. Down-converter 455 down-converts the received signal tobaseband frequency and removes cyclic prefix block 460 and removes thecyclic prefix to produce the serial time-domain baseband signal.Serial-to-parallel block 465 converts the time-domain baseband signal toparallel time-domain signals. Size N FFT block 470 then performs an FFTalgorithm to produce N parallel frequency-domain signals.Parallel-to-serial block 475 converts the parallel frequency-domainsignals to a sequence of modulated data symbols. Channel decoding anddemodulation block 480 demodulates and then decodes the modulatedsymbols to recover the original input data stream.

Each of gNBs 101-103 may implement a transmit path that is analogous totransmitting in the downlink to user equipment 111-116 and may implementa receive path that is analogous to receiving in the uplink from userequipment 111-116. Similarly, each one of user equipment 111-116 mayimplement a transmit path corresponding to the architecture fortransmitting in the uplink to gNBs 101-103 and may implement a receivepath corresponding to the architecture for receiving in the downlinkfrom gNBs 101-103.

5G communication system use cases have been identified and described.Those use cases can be roughly categorized into three different groups.In one example, enhanced mobile broadband (eMBB) is determined to dowith high bits/sec requirement, with less stringent latency andreliability requirements. In another example, ultra-reliable and lowlatency (URLL) is determined with less stringent bits/sec requirement.In yet another example, massive machine type communication (mMTC) isdetermined that a number of devices can be as many as 100,000 to 1million per km2, but the reliability/throughput/latency requirementcould be less stringent. This scenario may also involve power efficiencyrequirement as well, in that the battery consumption may be minimized aspossible.

A communication system includes a downlink (DL) that conveys signalsfrom transmission points such as base stations (BSs) or NodeBs to userequipments (UEs) and an Uplink (UL) that conveys signals from UEs toreception points such as NodeBs. A UE, also commonly referred to as aterminal or a mobile station, may be fixed or mobile and may be acellular phone, a personal computer device, or an automated device. AneNodeB, which is generally a fixed station, may also be referred to asan access point or other equivalent terminology. For LTE systems, aNodeB is often referred as an eNodeB.

In a communication system, such as LTE system, DL signals can includedata signals conveying information content, control signals conveying DLcontrol information (DCI), and reference signals (RS) that are alsoknown as pilot signals. An eNodeB transmits data information through aphysical DL shared channel (PDSCH). An eNodeB transmits DCI through aphysical DL control channel (PDCCH) or an Enhanced PDCCH (EPDCCH).

An eNodeB transmits acknowledgement information in response to datatransport block (TB) transmission from a UE in a physical hybrid ARQindicator channel (PHICH). An eNodeB transmits one or more of multipletypes of RS including a UE-common RS (CRS), a channel state informationRS (CSI-RS), or a demodulation RS (DMRS). A CRS is transmitted over a DLsystem bandwidth (BW) and can be used by UEs to obtain a channelestimate to demodulate data or control information or to performmeasurements. To reduce CRS overhead, an eNodeB may transmit a CSI-RSwith a smaller density in the time and/or frequency domain than a CRS.DMRS can be transmitted only in the BW of a respective PDSCH or EPDCCHand a UE can use the DMRS to demodulate data or control information in aPDSCH or an EPDCCH, respectively. A transmission time interval for DLchannels is referred to as a subframe and can have, for example,duration of 1 millisecond.

DL signals also include transmission of a logical channel that carriessystem control information. A BCCH is mapped to either a transportchannel referred to as a broadcast channel (BCH) when the DL signalsconvey a master information block (MIB) or to a DL shared channel(DL-SCH) when the DL signals convey a System Information Block (SIB).Most system information is included in different SIBs that aretransmitted using DL-SCH. A presence of system information on a DL-SCHin a subframe can be indicated by a transmission of a correspondingPDCCH conveying a codeword with a cyclic redundancy check (CRC)scrambled with system information RNTI (SI-RNTI). Alternatively,scheduling information for a SIB transmission can be provided in anearlier SIB and scheduling information for the first SIB (SIB-1) can beprovided by the MIB.

DL resource allocation is performed in a unit of subframe and a group ofphysical resource blocks (PRBs). A transmission BW includes frequencyresource units referred to as resource blocks (RBs). Each RB includesNR^(B) sub-carriers, or resource elements (REs), such as 12 REs. A unitof one RB over one subframe is referred to as a PRB. A UE can beallocated M_(PDSCH) RBs for a total of M_(sc) ^(PDSCH) M_(PDSCH)·N_(sc)^(RB) REs for the PDSCH transmission BW.

UL signals can include data signals conveying data information, controlsignals conveying UL control information (UCI), and UL RS. UL RSincludes DMRS and Sounding RS (SRS). A UE transmits DMRS only in a BW ofa respective PUSCH or PUCCH. An eNodeB can use a DMRS to demodulate datasignals or UCI signals. A UE transmits SRS to provide an eNodeB with anUL CSI. A UE transmits data information or UCI through a respectivephysical UL shared channel (PUSCH) or a Physical UL control channel(PUCCH). If a UE needs to transmit data information and UCI in a same ULsubframe, the UE may multiplex both in a PUSCH. UCI includes HybridAutomatic Repeat request acknowledgement (HARQ-ACK) information,indicating correct (ACK) or incorrect (NACK) detection for a data TB ina PDSCH or absence of a PDCCH detection (DTX), scheduling request (SR)indicating whether a UE has data in the UE's buffer, rank indicator(RI), and channel state information (CSI) enabling an eNodeB to performlink adaptation for PDSCH transmissions to a UE. HARQ-ACK information isalso transmitted by a UE in response to a detection of a PDCCH/EPDCCHindicating a release of semi-persistently scheduled PDSCH.

An UL subframe includes two slots. Each slot includes N_(symb) ^(UL)symbols for transmitting data information, UCI, DMRS, or SRS. Afrequency resource unit of an UL system BW is an RB. A UE is allocatedN_(RB) RBs for a total of N_(RB)·N_(sc) ^(RB) REs for a transmission BW.For a PUCCH, N_(RB)=1. A last subframe symbol can be used to multiplexSRS transmissions from one or more UEs. A number of subframe symbolsthat are available for data/UCI/DMRS transmission isN_(symb)=2·(N_(symb) ^(UL)−1)−N_(SRS), where N_(SRS)=1 if a lastsubframe symbol is used to transmit SRS and N_(SRS)=0 otherwise.

FIG. 5 illustrates a transmitter block diagram 500 for a PDSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the transmitter block diagram 500 illustrated in FIG. 5 isfor illustration only. One or more of the components illustrated in FIG.5 can be implemented in specialized circuitry configured to perform thenoted functions or one or more of the components can be implemented byone or more processors executing instructions to perform the notedfunctions. FIG. 5 does not limit the scope of this disclosure to anyparticular implementation of the transmitter block diagram 500.

As shown in FIG. 5 , information bits 510 are encoded by encoder 520,such as a turbo encoder, and modulated by modulator 530, for exampleusing quadrature phase shift keying (QPSK) modulation. A serial toparallel (S/P) converter 540 generates M modulation symbols that aresubsequently provided to a mapper 550 to be mapped to REs selected by atransmission BW selection unit 555 for an assigned PDSCH transmissionBW, unit 560 applies an Inverse fast Fourier transform (IFFT), theoutput is then serialized by a parallel to serial (P/S) converter 570 tocreate a time domain signal, filtering is applied by filter 580, and asignal transmitted 590. Additional functionalities, such as datascrambling, cyclic prefix insertion, time windowing, interleaving, andothers are well known in the art and are not shown for brevity.

FIG. 6 illustrates a receiver block diagram 600 for a PDSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the diagram 600 illustrated in FIG. 6 is for illustrationonly. One or more of the components illustrated in FIG. 6 can beimplemented in specialized circuitry configured to perform the notedfunctions or one or more of the components can be implemented by one ormore processors executing instructions to perform the noted functions.FIG. 6 does not limit the scope of this disclosure to any particularimplementation of the diagram 600.

As shown in FIG. 6 , a received signal 610 is filtered by filter 620,REs 630 for an assigned reception BW are selected by BW selector 635,unit 640 applies a fast Fourier transform (FFT), and an output isserialized by a parallel-to-serial converter 650. Subsequently, ademodulator 660 coherently demodulates data symbols by applying achannel estimate obtained from a DMRS or a CRS (not shown), and adecoder 670, such as a turbo decoder, decodes the demodulated data toprovide an estimate of the information data bits 680. Additionalfunctionalities such as time-windowing, cyclic prefix removal,de-scrambling, channel estimation, and de-interleaving are not shown forbrevity.

FIG. 7 illustrates a transmitter block diagram 700 for a PUSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the block diagram 700 illustrated in FIG. 7 is forillustration only. One or more of the components illustrated in FIG. 5can be implemented in specialized circuitry configured to perform thenoted functions or one or more of the components can be implemented byone or more processors executing instructions to perform the notedfunctions. FIG. 7 does not limit the scope of this disclosure to anyparticular implementation of the block diagram 700.

As shown in FIG. 7 , information data bits 710 are encoded by encoder720, such as a turbo encoder, and modulated by modulator 730. A discreteFourier transform (DFT) unit 740 applies a DFT on the modulated databits, REs 750 corresponding to an assigned PUSCH transmission BW areselected by transmission BW selection unit 755, unit 760 applies an IFFTand, after a cyclic prefix insertion (not shown), filtering is appliedby filter 770 and a signal transmitted 780.

FIG. 8 illustrates a receiver block diagram 800 for a PUSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the block diagram 800 illustrated in FIG. 8 is forillustration only. One or more of the components illustrated in FIG. 8can be implemented in specialized circuitry configured to perform thenoted functions or one or more of the components can be implemented byone or more processors executing instructions to perform the notedfunctions. FIG. 8 does not limit the scope of this disclosure to anyparticular implementation of the block diagram 800.

As shown in FIG. 8 , a received signal 810 is filtered by filter 820.Subsequently, after a cyclic prefix is removed (not shown), unit 830applies a FFT, REs 840 corresponding to an assigned PUSCH reception BWare selected by a reception BW selector 845, unit 850 applies an inverseDFT (IDFT), a demodulator 860 coherently demodulates data symbols byapplying a channel estimate obtained from a DMRS (not shown), a decoder870, such as a turbo decoder, decodes the demodulated data to provide anestimate of the information data bits 880.

In next generation cellular systems, various use cases are envisionedbeyond the capabilities of LTE system. Termed 5G or the fifth-generationcellular system, a system capable of operating at sub-6 GHz and above-6GHz (for example, in mmWave regime) becomes one of the requirements. In3GPP TR 22.891, 74 5G use cases have been identified and described;those use cases can be roughly categorized into three different groups.A first group is termed “enhanced mobile broadband (eMBB),” targeted tohigh data rate services with less stringent latency and reliabilityrequirements. A second group is termed “ultra-reliable and low latency(URLL)” targeted for applications with less stringent data raterequirements, but less tolerant to latency. A third group is termed“massive MTC (mMTC)” targeted for large number of low-power deviceconnections such as 1 million per km² with less stringent thereliability, data rate, and latency requirements.

The 3GPP NR specification supports up to 32 CSI-RS antenna ports whichenable a gNB to be equipped with a large number of antenna elements(such as 64 or 128). In this case, a plurality of antenna elements ismapped onto one CSI-RS port. For next generation cellular systems suchas 5G, the maximum number of CSI-RS ports can either remain the same orincrease.

FIG. 9 illustrates an example antenna blocks or arrays 900 according toembodiments of the present disclosure. The embodiment of the antennablocks or arrays 1100 illustrated in FIG. 9 is for illustration only.FIG. 9 does not limit the scope of this disclosure to any particularimplementation of the antenna blocks or arrays 900.

For mmWave bands, although the number of antenna elements can be largerfor a given form factor, the number of CSI-RS ports—which can correspondto the number of digitally precoded ports—tends to be limited due tohardware constraints (such as the feasibility to install a large numberof ADCs/DACs at mmWave frequencies) as illustrated in FIG. 9 . In thiscase, one CSI-RS port is mapped onto a large number of antenna elementswhich can be controlled by a bank of analog phase shifters 901. OneCSI-RS port can then correspond to one sub-array which produces a narrowanalog beam through analog beamforming 905. This analog beam can beconfigured to sweep across a wider range of angles (920) by varying thephase shifter bank across symbols or subframes. The number of sub-arrays(equal to the number of RF chains) is the same as the number of CSI-RSports N_(CSI-PORT). A digital beamforming unit 910 performs a linearcombination across N_(CSI-PORT) analog beams to further increaseprecoding gain. While analog beams are wideband (hence notfrequency-selective), digital precoding can be varied across frequencysub-bands or resource blocks.

To enable digital precoding, efficient design of CSI-RS is a crucialfactor. For this reason, three types of CSI reporting mechanismscorresponding to three types of CSI-RS measurement behavior aresupported, for example, “CLASS A” CSI reporting which corresponds tonon-precoded CSI-RS, “CLASS B” reporting with K=1 CSI-RS resource whichcorresponds to UE-specific beamformed CSI-RS, and “CLASS B” reportingwith K>1 CSI-RS resources which corresponds to cell-specific beamformedCSI-RS.

For non-precoded (NP) CSI-RS, a cell-specific one-to-one mapping betweenCSI-RS port and TXRU is utilized. Different CSI-RS ports have the samewide beam width and direction and hence generally cell wide coverage.For beamformed CSI-RS, beamforming operation, either cell-specific orUE-specific, is applied on a non-zero-power (NZP) CSI-RS resource (e.g.,comprising multiple ports). At least at a given time/frequency, CSI-RSports have narrow beam widths and hence not cell wide coverage, and atleast from the gNB perspective. At least some CSI-RS port-resourcecombinations have different beam directions.

In scenarios where DL long-term channel statistics can be measuredthrough UL signals at a serving eNodeB, UE-specific BF CSI-RS can bereadily used. This is typically feasible when UL-DL duplex distance issufficiently small. When this condition does not hold, however, some UEfeedback is necessary for the eNodeB to obtain an estimate of DLlong-term channel statistics (or any of representation thereof). Tofacilitate such a procedure, a first BF CSI-RS transmitted withperiodicity T1 (ms) and a second NP CSI-RS transmitted with periodicityT2 (ms), where T1≤T2. This approach is termed hybrid CSI-RS. Theimplementation of hybrid CSI-RS is largely dependent on the definitionof CSI process and NZP CSI-RS resource.

In the 3GPP LTE specification, MIMO has been identified as an essentialfeature in order to achieve high system throughput requirements and itwill continue to be the same in NR. One of the key components of a MIMOtransmission scheme is the accurate CSI acquisition at the eNB (or TRP).For MU-MIMO, in particular, the availability of accurate CSI isnecessary in order to guarantee high MU performance. For TDD systems,the CSI can be acquired using the SRS transmission relying on thechannel reciprocity. For FDD systems, on the other hand, the CSI can beacquired using the CSI-RS transmission from the eNB, and CSI acquisitionand feedback from the UE. In legacy FDD systems, the CSI feedbackframework is ‘implicit’ in the form of CQI/PMI/RI derived from acodebook assuming SU transmission from the eNB. Because of the inherentSU assumption while deriving CSI, this implicit CSI feedback isinadequate for MU transmission. Since future (e.g., NR) systems arelikely to be more MU-centric, this SU-MU CSI mismatch will be abottleneck in achieving high MU performance gains. Another issue withimplicit feedback is the scalability with larger number of antenna portsat the eNB. For large number of antenna ports, the codebook design forimplicit feedback is quite complicated, and the designed codebook is notguaranteed to bring justifiable performance benefits in practicaldeployment scenarios (for example, only a small percentage gain can beshown at the most).

In 5G or NR systems, the above-mentioned CSI reporting paradigm from LTEis also supported and referred to as Type I CSI reporting. In additionto Type I, a high-resolution CSI reporting, referred to as Type II CSIreporting, is also supported to provide more accurate CSI information togNB for use cases such as high-order MU-MIMO. The overhead of Type IICSI reporting can be an issue in practical UE implementations. Oneapproach to reduce Type II CSI overhead is based on frequency domain(FD) compression. In Rel. 16 NR, DFT-based FD compression of the Type IICSI has been supported (referred to as Rel. 16 enhanced Type II codebookin REF8). Some of the key components for this feature includes (a)spatial domain (SD) basis W₁, (b) FD basis W_(f), and (c) coefficients{tilde over (W)}₂ that linearly combine SD and FD basis. In anon-reciprocal FDD system, a complete CSI (comprising all components)needs to be reported by the UE. However, when reciprocity or partialreciprocity does exist between UL and DL, then some of the CSIcomponents can be obtained based on the UL channel estimated using SRStransmission from the UE. In Rel. 16 NR, the DFT-based FD compression isextended to this partial reciprocity case (referred to as Rel. 16enhanced Type II port selection codebook in REF8), wherein the DFT-basedSD basis in W₁ is replaced with SD CSI-RS port selection, i.e., L out ofP_(CSI-RS)/2 CSI-RS ports are selected (the selection is common for thetwo antenna polarizations or two halves of the CSI-RS ports). The CSI-RSports in this case are beamformed in SD (assuming UL-DL channelreciprocity in angular domain), and the beamforming information can beobtained at the gNB based on UL channel estimated using SRSmeasurements.

It has been known in the literature that UL-DL channel reciprocityexists in both angular and delay domains if the UL-DL duplexing distanceis small. Since delay in time domain transforms (or closely related to)basis vectors in frequency domain (FD), the Rel. 16 enhanced Type IIport selection can be further extended to both angular and delay domains(or SD and FD). In particular, the DFT-based SD basis in W₁ and/orDFT-based FD basis in W_(f) can be replaced with SD and FD portselection, i.e., L CSI-RS ports are selected in SD and/or M ports areselected in FD. The CSI-RS ports in this case are beamformed in SD(assuming UL-DL channel reciprocity in angular domain) and/or FD(assuming UL-DL channel reciprocity in delay/frequency domain), and thecorresponding SD and/or FD beamforming information can be obtained atthe gNB based on UL channel estimated using SRS measurements. In Rel. 17NR, such a codebook will be supported.

FIG. 10 illustrates channel measurement with and without Dopplercomponents 1000 according to embodiments of the present disclosure. Theembodiment of the channel measurement with and without Dopplercomponents 1000 illustrated in FIG. 10 is for illustration only. FIG. 10does not limit the scope of this disclosure to any particularimplementation of the channel measurement with and without Dopplercomponents 1000.

Now, when the UE speed is in a moderate or high-speed regime, theperformance of the Rel. 15/16/17 codebooks starts to deteriorate quicklydue to fast channel variations (which in turn is due to UE mobility thatcontributes to the Doppler component of the channel), and a one-shotnature of CSI-RS measurement and CSI reporting in Rel. 15/16/17. Thislimits the usefulness of Rel. 15/16/17 codebooks to low mobility orstatic UEs only. For moderate or high mobility scenarios, an enhancementin CSI-RS measurement and CSI reporting is needed, which is based on theDoppler components of the channel. As described in [REF9], the Dopplercomponents of the channel remain almost constant over a large timeduration, referred to as channel stationarity time, which issignificantly larger than the channel coherence time. Note that thecurrent (Rel. 15/16/17) CSI reporting is based on the channel coherencetime, which is not suitable when the channel has significant Dopplercomponents. The Doppler components of the channel can be calculatedbased on measuring a reference signal (RS) burst, where the RS can beCSI-RS or SRS. When the RS is CSI-RS, the UE measures a CSI-RS burst,and use it to obtain Doppler components of the DL channel, and when RSis SRS, the gNB measures an SRS burst, and use it to obtain Dopplercomponents of the UL channel. The obtained Doppler components can bereported by the UE using a codebook (as part of a CS report). Or the gNBcan use the obtained Doppler components of the UL channel to beamformCSI-RS for CSI reporting by the UE. An illustration of channelmeasurement with and without Doppler components is shown in FIG. 10 .When the channel is measured with the Doppler components (e.g., based onan RS burst), the measured channel can remain close to the actualvarying channel. On the other hand, when the channel is measured withoutthe Doppler components (e.g., based on a one-shot RS), the measuredchannel can be far from the actual varying channel.

As described, measuring an RS burst is needed in order to obtain theDoppler components of the channel. This disclosure provides severalexample embodiments on obtaining the Doppler domain components or unitsthat determine the length of the basis vectors that are used for theDoppler compression. The disclosure also describes example embodimentson signaling related to the CSI reporting format.

All the following components and embodiments are applicable for ULtransmission with CP-OFDM (cyclic prefix OFDM) waveform as well asDFT-SOFDM (DFT-spread OFDM) and SC-FDMA (single-carrier FDMA) waveforms.Furthermore, all the following components and embodiments are applicablefor UL transmission when the scheduling unit in time is either onesubframe (which can consist of one or multiple slots) or one slot.

In the present disclosure, the frequency resolution (reportinggranularity) and span (reporting bandwidth) of CSI reporting can bedefined in terms of frequency “subbands” and “CSI reporting band” (CRB),respectively.

A subband for CSI reporting is defined as a set of contiguous PRBs whichrepresents the smallest frequency unit for CSI reporting. The number ofPRBs in a subband can be fixed for a given value of DL system bandwidth,configured either semi-statically via higher-layer/RRC signaling, ordynamically via L1 DL control signaling or MAC control element (MAC CE).The number of PRBs in a subband can be included in CSI reportingsetting.

“CSI reporting band” is defined as a set/collection of subbands, eithercontiguous or non-contiguous, wherein CSI reporting is performed. Forexample, CSI reporting band can include all the subbands within the DLsystem bandwidth. This can also be termed “full-band”. Alternatively,CSI reporting band can include only a collection of subbands within theDL system bandwidth. This can also be termed “partial band”.

The term “CSI reporting band” is used only as an example forrepresenting a function. Other terms such as “CSI reporting subband set”or “CSI reporting bandwidth” can also be used.

In terms of UE configuration, a UE can be configured with at least oneCSI reporting band. This configuration can be semi-static (viahigher-layer signaling or RRC) or dynamic (via MAC CE or L1 DL controlsignaling). When configured with multiple (N) CSI reporting bands (e.g.,via RRC signaling), a UE can report CSI associated with n≤N CSIreporting bands. For instance, >6 GHz, large system bandwidth mayrequire multiple CSI reporting bands. The value of n can either beconfigured semi-statically (via higher-layer signaling or RRC) ordynamically (via MAC CE or L1 DL control signaling). Alternatively, theUE can report a recommended value of n via an UL channel.

Therefore, CSI parameter frequency granularity can be defined per CSIreporting band as follows. A CSI parameter is configured with “single”reporting for the CSI reporting band with M_(n) subbands when one CSIparameter for all the M_(n) subbands within the CSI reporting band. ACSI parameter is configured with “subband” for the CSI reporting bandwith M_(n) subbands when one CSI parameter is reported for each of theM_(n) subbands within the CSI reporting band.

FIG. 11 illustrates an example antenna port layout 1100 according toembodiments of the present disclosure. The embodiment of the antennaport layout 1100 illustrated in FIG. 11 is for illustration only. FIG.11 does not limit the scope of this disclosure to any particularimplementation of the antenna port layout 1100.

As illustrated in FIG. 11 , N₁ and N₂ are the number of antenna portswith the same polarization in the first and second dimensions,respectively. For 2D antenna port layouts, N₁>1, N₂>1, and for 1Dantenna port layouts N₁>1 and N₂₌₁. Therefore, for a dual-polarizedantenna port layout, the total number of antenna ports is 2N₁N₂.

As described in U.S. Pat. No. 10,659,118, issued May 19, 2020, andentitled “Method and Apparatus for Explicit CSI Reporting in AdvancedWireless Communication Systems,” which is incorporated herein byreference in its entirety, a UE is configured with high-resolution(e.g., Type II) CSI reporting in which the linear combination-based TypeII CSI reporting framework is extended to include a frequency dimensionin addition to the first and second antenna port dimensions.

FIG. 12 illustrates a 3D grid 1300 of the oversampled DFT beams (1stport dim., 2nd port dim., freq. dim.) in which

-   -   1st dimension is associated with the 1st port dimension,    -   2nd dimension is associated with the 2nd port dimension, and    -   3rd dimension is associated with the frequency dimension. The        basis sets for 1^(st) and 2^(nd) port domain representation are        oversampled DFT codebooks of length-N₁ and length-N₂,        respectively, and with oversampling factors O₁ and O₂,        respectively. Likewise, the basis set for frequency domain        representation (i.e., 3rd dimension) is an oversampled DFT        codebook of length-N₃ and with oversampling factor O₃. In one        example, O₁=O₂=O₃=4. In another example, the oversampling        factors O belongs to {2, 4, 8}. In yet another example, at least        one of O₁, O₂, and O₃ is higher layer configured (via RRC        signaling).

As explained in Section 5.2.2.2.6 of REF8, a UE is configured withhigher layer parameter codebookType set to ‘ typeII-PortSelection-r16’for an enhanced Type II CSI reporting in which the pre-coders for allSBs and for a given layer l=1, . . . , v, where v is the associated RIvalue, is given by either

$\begin{matrix}{{W^{l} = {{{AC}_{l}B^{H}} = {\left\lbrack {a_{0}a_{1}\ldots a_{L - 1}} \right\rbrack\begin{bmatrix}c_{l,0,0} & c_{l,0,1} & \ldots & c_{l,0,{M - 1}} \\c_{l,1,0} & c_{l,1,1} & \ldots & c_{l,1,{M - 1}} \\ \vdots & \vdots & \vdots & \vdots \\c_{l,{L - 1},0} & c_{l,{L - 1},1} & \ldots & c_{l,{L - 1},{M - 1}}\end{bmatrix}}}}\text{ }{{\left\lbrack {b_{0}b_{1}\ldots b_{M - 1}} \right\rbrack^{H} = {{\sum_{f = 0}^{M - 1}{\sum_{i = 0}^{L - 1}{c_{l,i,f}\left( {a_{i}b_{f}^{H}} \right)}}} = \text{ }{\sum_{i = 0}^{L - 1}{\sum_{f = 0}^{M - 1}{c_{l,i,f}\left( {a_{i}b_{f}^{H}} \right)}}}}},}} & \left( {{Eq}.1} \right)\end{matrix}$ or $\begin{matrix}{{W^{l} = {{\begin{bmatrix}A & 0 \\0 & A\end{bmatrix}C_{l}B^{H}} = \begin{bmatrix}{a_{0}a_{1}\ldots a_{L - 1}} & 0 \\0 & {a_{0}a_{1}\ldots a_{L - 1}}\end{bmatrix}}}\text{ }{{{\begin{bmatrix}c_{l,0,0} & c_{l,0,1} & \ldots & c_{l,0,{M - 1}} \\c_{l,1,0} & c_{l,1,1} & \ldots & c_{l,1,{M - 1}} \\ \vdots & \vdots & \vdots & \vdots \\c_{l,{L - 1},0} & c_{l,{L - 1},1} & \ldots & c_{l,{L - 1},{M - 1}}\end{bmatrix}\left\lbrack {b_{0}b_{1}\ldots b_{M - 1}} \right\rbrack}^{H} = \text{ }\begin{bmatrix}{\sum_{f = 0}^{M - 1}{\sum_{i = 0}^{L - 1}{c_{l,i,f}\left( {a_{i}b_{f}^{H}} \right)}}} \\{\sum_{f = 0}^{M - 1}{\sum_{i = 0}^{L - 1}{c_{l,{i + L},f}\left( {a_{i}b_{f}^{H}} \right)}}}\end{bmatrix}},}} & \left( {{Eq}.2} \right)\end{matrix}$

where

-   -   N₁ is a number of antenna ports in a first antenna port        dimension (having the same antenna polarization),    -   N₂ is a number of antenna ports in a second antenna port        dimension (having the same antenna polarization),    -   P_(CSI-RS) is a number of CSI-RS ports configured to the UE,    -   N₃ is a number of SBs for PMI reporting or number of FD units or        number of FD components (that comprise the CSI reporting band)        or a total number of precoding matrices indicated by the PMI        (one for each FD unit/component),    -   a_(i) is a 2N₁N₂×1 (Eq. 1) or N₁N₂×1 (Eq. 2) column vector, and        a_(i) is a N₁N₂×1 or

$\frac{P_{CSIRS}}{2} \times 1$

-   -    port selection column vector if antenna ports at the gNB are        co-polarized, and is a 2N₁N₂×1 or P_(CSIRS)×1 port selection        column vector if antenna ports at the gNB are dual-polarized or        cross-polarized, where a port selection vector is a defined as a        vector which contains a value of 1 in one element and zeros        elsewhere, and P_(CSIRS) is the number of CSI-RS ports        configured for CSI reporting,    -   b_(f) is a N₃×1 column vector,    -   c_(l,i,f) is a complex coefficient associate with vectors a_(i)        and b_(f).

In a variation, when the UE reports a subset K<2LM coefficients (where Kis either fixed, configured by the gNB or reported by the UE), then thecoefficient c_(l,i,f) in precoder equations Eq. 1 or Eq. 2 is replacedwith x_(l,i,f)×c_(l,i,f), where

-   -   x_(l,i,f)=1 if the coefficient c_(l,i,f) is reported by the UE        according to some embodiments of this disclosure.    -   x_(l,i,f)=0 otherwise (i.e., c_(l,i,f) is not reported by the        UE).        The indication whether x_(l,i,f)=1 or 0 is according to some        embodiments of this disclosure. For example, it can be via a        bitmap.

In a variation, the precoder equations Eq. 1 or Eq. 2 are respectivelygeneralized to

W ^(l)=Σ_(i=0) ^(L-1)Σ_(f=0) ^(M) ^(i) ⁻¹ c _(l,i,f)(a _(i) b _(i,f)^(H))  (Eq. 3)

and

$\begin{matrix}{{W^{l} = \begin{bmatrix}{\sum_{i = 0}^{L - 1}{\sum_{f = 0}^{M_{i} - 1}{c_{l,i,f}\left( {a_{i}b_{i,f}^{H}} \right)}}} \\{\sum_{i = 0}^{L - 1}{\sum_{= 0}^{M_{i} - 1}{c_{l,{i + L},f}\left( {a_{i}b_{i,f}^{H}} \right)}}}\end{bmatrix}},} & \left( {{Eq}.4} \right)\end{matrix}$

where for a given i, the number of basis vectors is M_(i) and thecorresponding basis vectors are {b_(i,f)}. Note that M_(i) is the numberof coefficients c_(l,i,f) reported by the UE for a given i, whereM_(i)≤M (where {M_(i)} or ΣM_(i) is either fixed, configured by the gNBor reported by the UE).

The columns of W^(i) are normalized to norm one. For rank R or R layers(v=R), the pre-coding matrix is given by

$W^{(R)} = {{\frac{1}{\sqrt{R}}\begin{bmatrix}\begin{matrix}\begin{matrix}W^{1} & W^{2}\end{matrix} & \ldots\end{matrix} & W^{R}\end{bmatrix}}.}$

Eq. 2 is assumed in the rest of the disclosure. The embodiments of thedisclosure, however, are general and are also application to Eq. 1, Eq.3, and Eq. 4.

Here

$L \leq {\frac{P_{{CSI} - {RS}}}{2}{and}M} \leq {N_{3}.}$

If

${L = \frac{P_{{CSI} - {RS}}}{2}},$

then A is an identity matrix, and hence not reported. Likewise, if M=N₃,then B is an identity matrix, and hence not reported. Assuming M<N₃, inan example, to report columns of B, the oversampled DFT codebook isused. For instance, b_(f)=w_(f), where the quantity w_(f) is given by

$w_{f} = {\begin{bmatrix}1 & e^{j\frac{2\pi n_{3,l}^{(f)}}{O_{3}N_{3}}} & e^{j\frac{2{\pi \cdot 2}n_{3,l}^{(f)}}{O_{3}N_{3}}} & \ldots & e^{j\frac{2{\pi \cdot {({N_{3} - 1})}}n_{3,l}^{(f)}}{O_{3}N_{3}}}\end{bmatrix}^{T}.}$

When O₃=1, the FD basis vector for layer l∈{1, . . . , v} (where v isthe RI or rank value) is given by

w _(f)=[y _(0,1) ^((f)) y _(1,l) ^((f)) . . . y _(N) _(3-1,i)^((f))]^(T),

where

$y_{t,l}^{(f)} = {{e^{j\frac{2\pi{tn}_{3,l}^{(f)}}{N_{3}}}{and}n_{3,l}} = \left\lbrack {n_{3,l}^{(0)},\ldots,n_{3,l}^{({M - 1})}} \right\rbrack}$

where n_(3,l) ^((f))∈{0, 1, . . . , N₃−1}.

In another example, discrete cosine transform DCT basis is used toconstruct/report basis B for the 3^(rd) dimension. The m-th column ofthe DCT compression matrix is simply given by

$\left\lbrack W_{f} \right\rbrack_{nm} = \left\{ {\begin{matrix}{\frac{1}{\sqrt{K}},{n = 0}} \\{{\sqrt{\frac{2}{k}}\cos\frac{{\pi\left( {{2m} + 1} \right)}n}{2K}},{n = 1},{{\ldots K} - 1}}\end{matrix},} \right.$ andK = N₃, andm = 0, …, N₃ − 1.

Since DCT is applied to real valued coefficients, the DCT is applied tothe real and imaginary components (of the channel or channeleigenvectors) separately. Alternatively, the DCT is applied to themagnitude and phase components (of the channel or channel eigenvectors)separately. The use of DFT or DCT basis is for illustration purposeonly. The disclosure is applicable to any other basis vectors toconstruct/report A and B.

On a high level, a precoder W¹ can be described as follows.

W=A _(l) C _(l) B _(l) ^(H) =W ₁

W _(f) ^(H),  (Eq. 5)

where A=W₁ corresponds to the Rel. 15 W₁ in Type II CSI codebook [REF8],and B=W_(f).

The C_(l)=

₂ matrix consists of all the required linear combination coefficients(e.g., amplitude and phase or real or imaginary). Each reportedcoefficient (c_(l,i,f)=p_(l,i,f)ϕ_(l,i,f)) in

₂ is quantized as amplitude coefficient (p_(l,i,f)) and phasecoefficient (ϕ_(l,i,f)). In one example, the amplitude coefficient(p_(l,i,f)) is reported using a A-bit amplitude codebook where A belongsto {2, 3, 4}. If multiple values for A are supported, then one value isconfigured via higher layer signaling. In another example, the amplitudecoefficient (p_(l,i,f)) is reported as p_(l,i,f)=p_(l,i,f) ⁽¹⁾p_(l,i,f)⁽²⁾ where

-   -   p_(l,i,f) ⁽¹⁾ is a reference or first amplitude which is        reported using a A1-bit amplitude codebook where A1 belongs to        {2, 3, 4}, and    -   p_(l,i,f) ⁽²⁾ is a differential or second amplitude which is        reported using a A2-bit amplitude codebook where A2≤A1 belongs        to {2, 3, 4}.

For layer l, let us denote the linear combination (LC) coefficientassociated with spatial domain (SD) basis vector (or beam) i∈{0, 1, . .. , 2L−1} and frequency domain (FD) basis vector (or beam) f∈{0, 1, . .. , M−1} as c_(l,i,f), and the strongest coefficient as c_(l,i*,f*). Thestrongest coefficient is reported out of the K_(NZ) non-zero (NZ)coefficients that is reported using a bitmap, whereK_(NZ)≤K₀=┌β×2LM┐<2LM and β is higher layer configured. The remaining2LM−K_(NZ) coefficients that are not reported by the UE are assumed tobe zero. The following quantization scheme is used to quantize/reportthe K_(NZ) NZ coefficients.

The UE reports the following for the quantization of the NZ coefficientsin {tilde over (W)}₂

-   -   A X-bit indicator for the strongest coefficient index (i*,f*),        where {tilde over (W)}=┌log₂ K_(NZ)┐ or ┌log₂ 2L┐.        -   Strongest coefficient c_(i,l*,f*)=1 (hence its            amplitude/phase are not reported)    -   Two antenna polarization-specific reference amplitudes are used.        -   For the polarization associated with the strongest            coefficient c_(l,i*,f*)=1, since the reference amplitude            p_(l,i,f) ⁽¹⁾=1, it is not reported        -   For the other polarization, reference amplitude p_(l,i,f)            ⁽¹⁾ is quantized to 4 bits            -   The 4-bit amplitude alphabet is

$\left\{ {1,\left( \frac{1}{2} \right)^{\frac{1}{4}},\left( \frac{1}{4} \right)^{\frac{1}{4}},\left( \frac{1}{8} \right)^{\frac{1}{4}},\ldots,\left( \frac{1}{2^{14}} \right)^{\frac{1}{4}}} \right\}.$

-   -   For {c_(l,i,f), (i,f)≠(i*,f*)}:        -   For each polarization, differential amplitudes p_(l,i,f) ⁽²⁾            of the coefficients calculated relative to the associated            polarization-specific reference amplitude and quantized to 3            bits            -   The 3-bit amplitude alphabet is

$\left\{ {1,\frac{1}{\sqrt{2}},\frac{1}{2},\frac{1}{2\sqrt{2}},\frac{1}{4},\frac{1}{4\sqrt{2}},\frac{1}{8},\frac{1}{8\sqrt{2}}} \right\}.$

-   -   -   -   Note: The final quantized amplitude p_(l,i,f) is given                by p_(l,i,f) ⁽¹⁾×p_(l,i,f) ⁽²⁾

        -   Each phase is quantized to either 8PSK (N_(ph)=8) or 16PSK            (N_(ph)=16) (which is configurable).

For the polarization r*∈{0, 1} associated with the strongest coefficientc_(l,i*,f*), we have

$r^{\star} = \left\lfloor \frac{i^{\star}}{L} \right\rfloor$

and the reference amplitude p_(l,i,f) ⁽¹⁾=p_(l,r*) ⁽¹⁾=1. For the otherpolarization r∈{0, 1} and r≠r*, we have

$r = \left( {\left\lfloor \frac{i^{\star}}{L} \right\rfloor + 1} \right)$

mod 2 and the reference amplitude p_(l,i,f) ⁽¹⁾=p_(l,r) ⁽¹⁾ is quantized(reported) using the 4-bit amplitude codebook mentioned above.

A UE can be configured to report M FD basis vectors. In one example,

${M = \left\lceil {p \times \frac{N_{3}}{R}} \right\rceil},$

where R is higher-layer configured from {1, 2} and p is higher-layerconfigured from

$\left\{ {\frac{1}{4},\frac{1}{2}} \right\}.$

In one example, the p value is higher-layer configured for rank 1-2 CSIreporting. For rank >2 (e.g., rank 3-4), the p value (denoted by v₀) canbe different. In one example, for rank 1-4, (p, v₀) is jointlyconfigured from

$\left\{ {\left( {\frac{1}{2},\frac{1}{4}} \right),\left( {\frac{1}{4},\frac{1}{4}} \right),\left( {\frac{1}{4},\frac{1}{8}} \right)} \right\},{i.e.},{M = \left\lceil {p \times \frac{N_{3}}{R}} \right\rceil}$

for rank 1-2 and

$M = \left\lceil {v_{0} \times \frac{N_{3}}{R}} \right\rceil$

for rank 3-4. In one example, N₃=N_(SB)×R where N_(SB) is the number ofSBs for CQI reporting. In the rest of the disclosure, M is replaced withM_(v) to show its dependence on the rank value v, hence p is replacedwith p_(v), v∈{1, 2} and v₀ is replaced with p_(v), v∈{3, 4}.

A UE can be configured to report M_(v) FD basis vectors in one-step fromN₃ basis vectors freely (independently) for each layer l∈{0, 1, . . . ,v−1} of a rank v CSI reporting. Alternatively, a UE can be configured toreport M_(v) FD basis vectors in two-step as follows.

-   -   In step 1, an intermediate set (InS) comprising N₃′<N₃ basis        vectors is selected/reported, wherein the InS is common for all        layers.    -   In step 2, for each layer l∈{0, 1, . . . , v−1} of a rank v CSI        reporting, M FD basis vectors are selected/reported freely        (independently) from N₃ basis vectors in the InS.

In one example, one-step method is used when N₃≤19 and two-step methodis used when N₃>19. In one example, N₃′=┌αM┐ where α>1 is either fixed(to 2 for example) or configurable.

The codebook parameters used in the DFT based frequency domaincompression (Eq. 5) are (L, p_(v) for v∈{1, 2}, p_(v) for v∈{3, 4}, β,α, N_(ph)). In one example, the set of values for these codebookparameters are as follows.

-   -   L: the set of values is {2, 4} in general, except L∈{2, 4, 6}        for rank 1-2, 32 CSI-RS antenna ports, and R=1.    -   (p_(v) for v∈{1, 2}, p_(v) for

$\left. {\upsilon \in \left\{ {3,4} \right\}} \right) \in {\left\{ {\left( {\frac{1}{2},\frac{1}{4}} \right),\left( {\frac{1}{4},\frac{1}{4}} \right),\left( {\frac{1}{4},\frac{1}{8}} \right)} \right\}.}$$\beta \in {\left\{ {\frac{1}{4},\frac{1}{2},\frac{3}{4}} \right\}.}$

-   -   α∈{1.5, 2, 2.5, 3}    -   N_(ph)∈{8, 16}.

In another example, the set of values for these codebook parameters areas follows: α=2, N_(ph)=16, and as in Table 1, where the values of L, βand p_(v) are determined by the higher layer parameterparamCombination-r17. In one example, the UE is not expected to beconfigured with paramCombination-r17 equal to

-   -   3, 4, 5, 6, 7, or 8 when P_(CSI-RS)=4,    -   7 or 8 when number of CSI-RS ports P_(CSI-RS)<32,    -   7 or 8 when higher layer parameter typeII-RI-Restriction-r17 is        configured with r_(i)=1 for any i>1,    -   7 or 8 when R=2.

The bitmap parameter typeII-RI-Restriction-r17 forms the bit sequencer₃, r₂, r₁, r₀ where r₀ is the LSB and r₃ is the MSB. When r_(i) iszero, i∈{0, 1, . . . , 3}, PMI and RI reporting are not allowed tocorrespond to any precoder associated with v=i+1 layers. The parameter Ris configured with the higher-layer parameternumberOfPMISubbandsPerCQISubband-r17. This parameter controls the totalnumber of precoding matrices N₃ indicated by the PMI as a function ofthe number of subbands in csi-ReportingBand, the subband size configuredby the higher-level parameter subbandSize and of the total number ofPRBs in the bandwidth part.

TABLE 1 P_(v) paramCombination- v v r17 L ϵ {1, 2} ϵ {3, 4} β 1 2 ¼ 1/8¼ 2 2 ¼ 1/8 ½ 3 4 ¼ 1/8 ¼ 4 4 ¼ 1/8 ½ 5 4 ¼ ¼ ¾ 6 4 ½ ¼ ½ 7 6 ¼ ½ 8 6 ¼— ¾

The above-mentioned framework (equation 5) represents theprecoding-matrices for multiple (N₃) FD units using a linear combination(double sum) over 2L SD beams and M_(v) FD beams. This framework canalso be used to represent the precoding-matrices in time domain (TD) byreplacing the FD basis matrix W_(f) with a TD basis matrix W_(t),wherein the columns of W_(t) comprises M_(v) TD beams that representsome form of delays or channel tap locations. Hence, a precoder W¹ canbe described as follows.

W=A _(l) C _(l) B _(l) ^(H) =W ₁

W _(t) ^(H),  (Equation 5A)

In one example, the M_(v) TD beams (representing delays or channel taplocations) are selected from a set of N₃ TD beams, i.e., N₃ correspondsto the maximum number of TD units, where each TD unit corresponds to adelay or channel tap location. In one example, a TD beam corresponds toa single delay or channel tap location. In another example, a TD beamcorresponds to multiple delays or channel tap locations. In anotherexample, a TD beam corresponds to a combination of multiple delays orchannel tap locations.

The abovementioned framework for CSI reporting based on space-frequencycompression (equation 5) or space-time compression (equation 5A)frameworks can be extended to Doppler domain (e.g., for moderate to highmobility UEs). This disclosure focuses on a CS-RS burst that can be usedto obtain Doppler component(s) of the channel, which can be used toperform Doppler domain (DD) or time domain (TD) compression. Inparticular, the disclosure provides embodiments regarding thegranularity or unit of the components across which the TD/DD compressionis performed, where each component corresponds to one or multiple timeinstances within a CSI-RS burst or across multiple CSI-RS bursts.

This disclosure focuses on a reference signal burst that can be used toobtain Doppler component(s) of the channel, which can be used to performDoppler domain compression.

FIG. 13 illustrates an example of a UE configured to receive a burst ofnon-zero power (NZP) CSI-RS resource(s) 1300 according to embodiments ofthe present disclosure. The embodiment of the UE configured to receivethe burst of NZP CSI-RS resource(s) 1300 illustrated in FIG. 13 is forillustration only. FIG. 13 does not limit the scope of this disclosureto any particular implementation of the UE configured to receive a burstof NZP CSI-RS resource(s) 1300.

In one embodiment, as shown in FIG. 13 , a UE is configured to receive aburst (or occasions) of non-zero power (NZP) CSI-RS resource(s),referred to as CSI-RS burst (or occasions) for brevity, in B time slots,where B≥1. The B time slots can be accordingly to at least one of thefollowing examples.

-   -   In one example, the B time slots are evenly/uniformly spaced        with an inter-slot spacing d.    -   In one example, the B time slots can be non-uniformly spaced        with inter-slot spacing e₁=d₁, e₂=d₂−d₁, e₃=d₃−d₂, . . . , so        on, where e_(i)≠e_(j) for at least one pair (i,j) with i≠j.

The UE receives the CSI-RS burst, estimates the B instances of the DLchannel measurements, and uses the channel estimates to obtain theDoppler component(s) of the DL channel. The CSI-RS burst can be linkedto (or associated with) a single CSI reporting setting (e.g., via higherlayer parameter CSI-ReportConfig), wherein the corresponding CSI reportincludes an information about the Doppler component(s) of the DLchannel.

Let h_(t) be the DL channel estimate based on the CSI-RS resource(s)received in time slot t∈{0, 1, . . . , B−1}. When the DL channelestimate in slot t is a matrix G_(t) of size N_(Rx)×N_(Tx)×N_(Sc), thenh_(t)=vec(G_(t)), where N_(Rx), N_(Tx), and N_(Sc) are number of receive(Rx) antennae at the UE, number of CSI-RS ports measured by the UE, andnumber of subcarriers in frequency band of the CSI-RS burst,respectively. The notation vec(X) is used to denote the vectorizationoperation wherein the matrix X is transformed into a vector byconcatenating the elements of the matrix in an order, for example, 1→2→34 and so on, implying that the concatenation starts from the firstdimension, then moves second dimension, and continues until the lastdimension. Let H_(B)=[h₀ h₁ . . . h_(B-1)] be a concatenated DL channel.The Doppler component(s) of the DL channel can be obtained based onH_(B). For example, H_(B) can be represented as CΦ^(H)=Σ_(s=0)^(N-1)c_(s)ϕ_(s) ^(H) where Φ=[℠₀ϕ₁ . . . ϕ_(N-1)] is a Doppler domain(DD) or TD basis matrix whose columns comprise basis vectors, C=[c₀ c₁ .. . c_(N-1)] is a coefficient matrix whose columns comprise coefficientvectors, and N<B is the number of DD or TD basis vectors. Since thecolumns of H_(B) are likely to be correlated, a DD or TD compression canbe achieved when the value of N is small (compared to the value of B).In this example, the Doppler component(s) of the channel is representedby the DD or TD basis matrix Φ and the coefficient matrix C.

FIG. 14 illustrates an example of a UE configured to determine a valueof N₄ based on the value B in a CSI-RS burst and a sub-time unit sizeN_(ST) 1400 according to embodiments of the present disclosure. Theembodiment of the UE configured to determine a value of N₄ based on thevalue B in a CSI-RS burst and a sub-time unit size N_(ST) 1400illustrated in FIG. 14 is for illustration only. FIG. 14 does not limitthe scope of this disclosure to any particular implementation of the UEconfigured to determine a value of N₄ based on the value B in a CSI-RSburst and a sub-time unit size N_(ST) 1400.

Let N₄ be the length of the basis vectors {ϕ_(S)}, e.g., each basisvector is a length N₄×1 column vector.

In one embodiment, a UE is configured to determine a value of N₄ basedon the value B (number of CSI-RS instances) in a CSI-RS burst andcomponents across which the DD or TD compression is performed, whereeach component corresponds to one or multiple time instances within theCSI-RS burst. In one example, N₄ is fixed (e.g., N₄=B) or configured(e.g., via RRC or MAC CE or DCI) or reported by the UE (as part of theCSI report). In one example, the B CSI-RS instances can be partitionedinto sub-time (ST) units (instances), where each ST unit is defined as(up to) N_(ST) contiguous time instances in the CSI-RS burst. In thisexample, a component for the DD or TD compression corresponds to a STunit. Three examples of the ST units are shown in FIG. 14 . In the firstexample, each ST unit comprises N_(ST)=1 time instance in the CSI-RSburst. In the second example, each ST unit comprises N_(ST)=2 contiguoustime instances in the CSI-RS burst. In the third example, each ST unitcomprises N_(ST)=4 contiguous time instances in the CSI-RS burst.

The value of N_(ST) can be fixed (e.g., N_(ST)=1 or 2 or 4) or indicatedto the UE (e.g., via higher layer RRC or MAC CE or DCI based signaling)or reported by the UE (e.g., as part of the CSI report). The value ofN_(ST) (fixed or indicated or reported) can be subject to a UEcapability reporting. The value of N_(ST) can also be dependent on thevalue of B (e.g., one value for a range of values for B and anothervalue for another range of values for B).

FIG. 15 illustrates an example of a UE configured to determine a valueof a frequency-domain unit and a value of time/Doppler domain unit basedon J≥1 CSI-RS bursts that occupy a frequency band and a time span 1500according to embodiments of the present disclosure. The embodiment ofthe UE configured to determine a value of a frequency-domain unit and avalue of time/Doppler domain unit based on J≥1 CSI-RS bursts that occupya frequency band and a time span 1500 illustrated in FIG. 15 is forillustration only. FIG. 15 does not limit the scope of this disclosureto any particular implementation of the UE configured to determine avalue of a frequency-domain unit and a value of time/Doppler domain unitbased on J≥1 CSI-RS bursts that occupy a frequency band and a time span1500.

In one embodiment, a UE is configured with J≥1 CSI-RS bursts (asillustrated earlier in the disclosure) that occupy a frequency band anda time span (duration), wherein the frequency band comprises A RBs, andthe time span comprises B time instances (of CSI-RS resource(s)) or C orB+C time instances, as described above. When j>1, the A RBs and/or Ytime instances (where Y=B or C or B+C) can be aggregated across J CSI-RSbursts. In one example, the frequency band equals the CSI reportingband, and the time span equals the number of CSI-RS resource instances(across J CSI-RS bursts) or the time span/window during which the CSIreport is expected to be valid, both can be configured to the UE for aCSI reporting, which can be based on the DD or TD compression.

The UE is further configured to partition (divide) the A RBs intosubbands (SBs) and/or the Y time instances into sub-times (STs). Thepartition of A RBs can be based on a SB size value N_(SB), which can beconfigured to the UE (cf. Table 5.2.1.4-2 of REF8). The partition of Ytime instances can be based either on an ST size value N_(ST) or on an rvalue, as described in this disclosure. An example is illustrated inFIG. 15 for Y=B, where RB0, RB1, . . . , RB_(A-1) comprise A RBs, T₀,T₁, . . . , T_(B-1) comprise B time instances, the SB size N_(SB)=4, andthe ST size N_(ST)=2.

The CSI reporting is based on channel measurements (based on CSI-RSbursts) in three-dimensions (3D): the first dimension corresponds to SDcomprising 2N₁N₂ or P_(CSIRS) CSI-RS antenna ports, the second dimensioncorresponds to FD comprising N₃ FD units (e.g., SB), and the thirddimension corresponds to DD or TD comprising N₄ DD or TD units (e.g.,ST). The 3D channel measurements can be compressed using basis vectors(or matrices) similar to the Rel. 16 enhanced Type II codebook. Let W₁,W_(f), and W_(d) respectively denote basis matrices whose columnscomprise basis vectors for SD, FD, and DD or TD.

In one embodiment, the UE is configured to report a CSI determined basedon a codebook comprising components: (A) three separate basis matricesW₁, W_(f), and W_(d) for SD, FD, and DD or TD compression, respectively,and (B) coefficients {tilde over (W)}₂. In particular, the precoder forlayer l is given by

W _(l) =A _(l) C _(l) B _(l) ^(H) =W ₁ {tilde over (W)} ₂ W _(f,d) ^(H)

Here W₁ is a P_(CSIRS)×N₃N₄ matrix whose columns are precoding vectorsfor N₃N₄ pairs of (FD, DD/TD) units, W₁ is a P_(CSIRS)×2L or P_(CSIRS)×LSD basis matrix (similar to Rel. 16 enhanced Type II codebook), {tildeover (W)}₂ is a 2L×M_(v)N coefficients matrix, and W_(f,d,l) is aN₃N₄×M₁N basis matrix for (FD, DD/TD) pairs. The columns of W_(f,d,l)comprises vectors v_(f,d,l) that are Kronecker products (KPs) of vectorsg_(f,l) and h_(d,l), columns of W_(f) and W_(d), respectively. W_(f) isa N₃×M_(v) FD basis matrix (similar to Rel. 16 enhanced Type IIcodebook) and W_(d) is a N₄×N DD basis matrix.

In one example, v_(f,d,l)=[g_(f,l)ϕ_(0,l) ^((d)) g_(f,l)ϕ_(1,l) ^((d)) .. . g_(f,l)ϕ_(N) ₄ _(-1,l) ^((d))]^(T)=[ϕ_(0,l) ^((d))g_(f,l) ϕ_(1,l)^((d))g_(f,l) . . . ϕ_(N) ₄ _(-1,i) ^((d))g_(f,l)]^(T), the KP ofh_(d,l) and g_(f,l).

In one example, v_(f,d,l)=[h_(d,l)y_(0,l) ^((f)) h_(d,l)y_(1,l) ^((f)) .. . h_(d,l)y_(N) ₃ _(-1,l) ^((f))]^(T)=[y_(0,l) ^((f))h_(d,l) y_(1,l)^((f))h_(d,l) . . . y_(N) ₃ _(-1,i) ^((f))h_(d,l)]^(T), the KP ofg_(f,l) and h_(d,l).

Here, g_(f,l)=[y_(0,l) ^((f)) y_(1,l) ^((f)) . . . y_(N) ₃ _(-1,l)^((f))] and h_(d,l)=[ϕ_(0,l) ^((d)) ϕ_(1,l) ^((d)) . . . ϕ_(N) ₄ _(-1,l)^((d))].

At least one of the following examples is used/configured regarding thereporting of the three bases.

-   -   In one example, all three bases are reported by the UE, e.g.,        via a component or more than one component of the PMI.    -   In one example, 2 out of 3 bases are reported, and the 3^(rd)        basis is either fixed, or configured (e.g., via RRC, MAC CE, or        DCI).        -   In one example, the 2 reported bases correspond to SD and FD            bases, and the 3^(rd) basis corresponds to the DD/TD basis.        -   In one example, the 2 reported bases correspond to SD and            DD/TD bases, and the 3^(rd) basis corresponds to the FD            basis.        -   In one example, the 2 reported bases correspond to FD and            DD/TD bases, and the 3^(rd) basis corresponds to the SD            basis.    -   In one example, 1 out of 3 bases is reported, and one or both of        the other two bases is either fixed, or configured (e.g., via        RRC, MAC CE, or DCI).        -   In one example, the 1 reported basis corresponds to the SD            basis, and the other two bases correspond to the FD and            DD/TD bases.        -   In one example, the 1 reported basis corresponds to the FD            basis, and the other two bases correspond to the SD and            DD/TD bases.        -   In one example, the 1 reported basis corresponds to the            DD/TD basis, and the other two bases correspond to the SD            and FD bases.

At least one of the following examples is used/configured regarding thethree basis matrices.

In one, when W₁ is a P_(CSIRS)×2L, the L SD basis vectors are determinedthe same way as in Rel. 15/16 Type II codebooks (cf. 5.2.2.2.3, REF 8),i.e., the SD basis vectors v_(m) ₁ _((i)) _(,m) ₂ _((i)) , i=0, 1, . . ., L−1, are identified by the indices q₁, q₂, n₁, n₂, can be indicated byPMI components i_(1,1), i_(1,2), and are obtained as in 5.2.2.2.3 of[REF 8].

The M_(v) FD basis vectors, g_(f,l)=[y_(0,l) ^((f)) y_(1,l) ^((f)) . . .y_(N) ₃ _(-1,l) ^((f))], f=0, 1, . . . , M_(v)−1, are identified byn_(3,l) (l=1, . . . , v) where

n _(3,l)=[n _(3,l) ⁽⁰⁾ , . . . ,n _(3,l) ^((M) ^(v) ⁻¹⁾]

n _(3,l) ^((f))∈{0,1, . . . ,N ₃−1}

The vector y_(t,l)=[y_(t,l) ⁽⁰⁾ y_(t,l) ⁽¹⁾ . . . y_(t,l) ^((M) ^(v)⁻¹⁾] comprises entries of FD basis vectors with FD index t={0, 1, . . ., N₃−1}, which is an (FD) index associated with the precoding matrix.

The N DD/TD basis vectors, h_(d,l)=[ϕ_(0,l) ^((d)) ϕ_(1,l) ^((d)) . . .ϕ_(n) ₄ _(-1,l) ^((d))], d=0, 1, . . . , N−1, are identified by n_(4,l)(l=1, . . . , v) where

n _(4,l)=[n _(4,l) ⁽⁰⁾ , . . . ,n _(4,l) ^((N-1))]

n _(4,l) ^((d))∈{0,1, . . . ,N ₄−1}

The vector ϕ_(u,l)=[ϕ_(u,l) ⁽⁰⁾ ϕ_(u,l) ⁽¹⁾ . . . ϕ_(u,l) ^((N-1))]comprises entries of DD/TD basis vectors with DD/TD index u={0, 1, . . ., N₄−1}, which is an (DD/TD) index associated with the precoding matrix.

In one example, the FD basis vectors are orthogonal DFT vectors, and

$y_{t,l}^{(f)} = {e^{j\frac{2\pi{tn}_{3,l}^{(f)}}{N_{3}}}.}$

In one example, the DD/TD basis vectors are orthogonal DFT vectors, and

$\phi_{u,l}^{(d)} = {e^{j\frac{2\pi{un}_{4,l}^{(d)}}{N_{4}}}.}$

In one example, the FD basis vectors are oversampled (or rotated)orthogonal DFT vectors with the oversampling (rotation) factor O₃, and

${y_{t,l}^{(f)} = e^{j\frac{2\pi tn_{3,l}^{(f)}}{O_{3}N_{3}}}},$

and the M_(v) FD basis vectors are also identified by the rotation indexq_(3,l){0, 1, . . . , O₃−1}. In one example, the DD/TD basis vectors areoversampled (or rotated) orthogonal DFT vectors with the oversampling(rotation) factor O₄, and

$\phi_{u,l}^{(d)} = e^{j\frac{2\pi{un}_{4,l}^{(d)}}{O_{4}N_{4}}}$

and the N DD/TD basis vectors are also identified by the rotation indexq_(4,l)∈{0, 1, . . . , O₄−1}. In one example, O₃ is fixed (e.g., 4), orconfigured (e.g., via RRC), or reported by the UE. In one example, O₄ isfixed (e.g., 4), or configured (e.g., via RRC), or reported by the UE.In one example, the rotation factor is layer-common (one value for alllayers), i.e., q_(3,l)=q₃ or q_(4,l)=q₄.

The precoders for v layers are then given by

${W_{\ldots,t,u}^{l} = {\frac{1}{\sqrt{N_{1}N_{2}\gamma_{t,u,l}}}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{(f)}\phi_{u,l}^{(d)}x_{l,i,f,d}}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{(f)}\phi_{u,l}^{(d)}x_{l,{i + L},f,d}}}}}}\end{bmatrix}}},{l = 1},\ldots,\upsilon,$γ_(t, u, l) = Σ_(i = 0)^(2L − 1)❘Σ_(f = 0)^(M_(υ) − 1)Σ_(d = 0)^(N − 1)y_(t, l)^((f))ϕ_(u, l)^((d))x_(l, i, f, d)❘²,

where x_(l,i,f,d) is the coefficient (an element of {tilde over (W)}₂)associated with codebook indices (l, i, f, d), where i is a row index of{tilde over (W)}₂ and (f, d) determine the column index k of {tilde over(W)}₂.In one example, f=k mod M_(v) and

${d = \frac{k - f}{M_{\upsilon}}},$

where k∈{0, 1, . . . , M_(v)N} is a column index of {tilde over (W)}₂.Here, k=M_(v)d+f.

In one example, d=k mod N and

$f = {\frac{k - d}{N}.}$

Here, k=Nf+d.

In one example,

$x_{l,i,f,d} = {p_{l,{\lfloor\frac{i}{L}\rfloor}}^{(1)}p_{l,i,f,d}^{(2)}\varphi_{l,i,f,d}}$

similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF8). Then,

${W_{\ldots,t,u}^{l} = {\frac{1}{\sqrt{N_{1}N_{2}\gamma_{t,u,l}}}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}p_{l,0}^{(1)}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{(f)}\phi_{u,l}^{(d)}p_{l,i,f,d}^{(2)}\varphi_{l,i,f,d}}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}p_{l,1}^{(1)}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{(f)}\phi_{u,l}^{(d)}p_{l,{i + L},f,d}^{(2)}\varphi_{l,{i + L},f,d}}}}}}\end{bmatrix}}},{l = 1},\ldots,\upsilon,$${\gamma_{t,u,l} = {{\Sigma_{i = 0}^{{2L} - 1}\left( p_{l,{\lfloor\frac{i}{L}\rfloor}}^{(1)} \right)}^{2}{❘{\Sigma_{f = 0}^{M_{\upsilon} - 1}\Sigma_{d = 0}^{N - 1}y_{t,l}^{(f)}\phi_{u,l}^{(d)}p_{l,i,f,d}^{(2)}\varphi_{l,i,f,d}}❘}^{2}}},$

and the quantities ϕ_(l,i,f,d) and p_(l,0) ⁽¹⁾, p_(l,1) ⁽¹⁾, p_(l,i,f,d)⁽²⁾ correspond to ϕ_(l,i,f) and p_(l,0) ⁽¹⁾, p_(l,1) ⁽¹⁾, p_(l,i,f) ⁽²⁾,respectively, as described in 5.2.2.2.5 of [REF 8].

In a variation, when W₁ is a P_(CSIRS)×L, and is not common for twoantenna polarizations, the precoders for v layers are then given by

${W_{\ldots,t,u}^{l} = {\frac{1}{\sqrt{N_{1}N_{2}\gamma_{t,u,l}}}\left\lbrack {\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{(f)}\phi_{u,l}^{(d)}x_{l,i,f,d}}}}}} \right\rbrack}},{l = 1},\ldots,\upsilon,$γ_(t, u, l) = Σ_(i = 0)^(L − 1)❘Σ_(f = 0)^(M_(υ) − 1)Σ_(d = 0)^(N − 1)y_(t, l)^((f))ϕ_(u, l)^((d))x_(l, i, f, d)❘²,

Where v_(m) ₁ _((i)) _(,m) ₂ _((i)) is a P_(CSIRS)×1 or 2N₁N₂×1 FD basisvector.

In one example, when W₁ is a P_(CSIRS)×2L, the L SD basis vectors aredetermined as in example I.1.1. The M_(v)N basis vectorsv_(k,l)=v_(f,d,l)=[y_(0,l) ^((k)) y_(1,l) ^((k)) . . . y_(N) ₃ _(N) ₄_(-1,l) ^((k))], k=0, 1, . . . , M_(v)N−1, are determined based on theM_(v) FD basis vectors, g_(f,l)=[y_(0,l) ^((f)) y_(1,l) ^((f)) . . .y_(N) ₃ _(-1,l) ^((f))], f=0, 1, . . . , M_(v)−1, and DD/TD basisvectors, h_(d,l)=[ϕ_(0,l) ^((d)) ϕ_(1,l) ^((d)) . . . ϕ_(N) ₄ _(-1,l)^((d))], d=0, 1, . . . , N−1. The index k determines (f, d) as explainedin example I.1.1. The details of g_(f,l) and h_(d,l) are as in exampleI.1.1.

The vector y_(t,u,l)=[y_(t,u,l) ⁽⁰⁾ y_(t,u,l) ⁽¹⁾ . . . y_(t,u,l) ^((M)^(v) ^(N-1))] comprises entries of FD basis vectors with FD index t={0,1, . . . , N₃−1} and entries of DD/TD basis vectors with DD/TD indexu={0, 1, . . . , N₄−1}, and (t, u) is an (FD, DD/TD) index pairassociated with the precoding matrix.

The precoders for v layers are given by

${W_{\ldots,t,u}^{l} = {\frac{1}{\sqrt{N_{1}N_{2}\gamma_{t,u,l}}}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,u,l}^{(k)}x_{l,i,f,d}}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,u,l}^{(k)}x_{l,{i + L},f,d}}}}}}\end{bmatrix}}},{l = 1},\ldots,\upsilon,$γ_(t, u, l) = Σ_(i = 0)^(2L − 1)❘Σ_(f = 0)^(M_(υ) − 1)Σ_(d = 0)^(N − 1)y_(t, u, l)^((k))x_(l, i, f, d)❘²,

where x_(l,i,f,d) is the coefficient (an element of {tilde over (W)}₂)associated with indices (l, i, f, d), where i is a row index of {tildeover (W)}₂ and (f, d) determine the column index k of {tilde over (W)}₂.In one example, f=k mod M_(v) and

${d = \frac{k - f}{M_{\upsilon}}},$

where k∈{0, 1, . . . , M_(v)N} is a column index of {tilde over (W)}₂.Here, k=M_(v)d+f.

In one example, d=k mod N and

$f = {\frac{k - d}{N}.}$

Here, k=Nf+d.

In one example,

$x_{l,i,f,d} = {p_{l,{\lfloor\frac{i}{L}\rfloor}}^{(1)}p_{l,i,f,d}^{(2)}\varphi_{l,i,f,d}}$

as in Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF 8).Then,

${W_{\ldots,t,u}^{l} = {\frac{1}{\sqrt{N_{1}N_{2}\gamma_{t,u,l}}}\begin{bmatrix}{\overset{L - 1}{\sum\limits_{i = 0}}{v_{m_{1}^{(i)},m_{2}^{(i)}}p_{l,0}^{(1)}{\overset{M_{v} - 1}{\sum\limits_{f = 0}}{\overset{N - 1}{\sum\limits_{d = 0}}{y_{t,u,l}^{(k)}p_{l,i,f,d}^{(2)}\varphi_{l,i,f,d}}}}}} \\{\overset{L - 1}{\sum\limits_{i = 0}}{v_{m_{1}^{(i)},m_{2}^{(i)}}p_{l,1}^{(1)}{\overset{M_{v} - 1}{\sum\limits_{f = 0}}{\overset{N - 1}{\sum\limits_{d = 0}}{y_{t,u,l}^{(k)}p_{l,{i + L},f,d}^{(2)}\varphi_{l,{i + L},f,d}}}}}}\end{bmatrix}}},{l = 1},\ldots,v,$$\gamma_{t,u,l} = {\sum_{i = 0}^{{2L} - 1}{\left( p_{l,{\lfloor\frac{i}{L}\rfloor}}^{(1)} \right)^{2}{{❘{\sum_{f = 0}^{M_{v} - 1}{\sum_{d = 0}^{N - 1}{y_{t,u,l}^{(k)}p_{l,i,f,d}^{(2)}\varphi_{l,i,f,d}}}}❘}^{2}.}}}$

and the quantities ϕ_(l,i,f,d) and p_(l,0) ⁽¹⁾, p_(l,1) ⁽¹⁾, p_(l,i,f,d)⁽²⁾ correspond to ϕ_(l,i,f) and p_(l,0) ⁽¹⁾, p_(l,1) ⁽¹⁾, p_(l,i,f) ⁽²⁾,respectively, as described in 5.2.2.2.5 of [REF 8].

In a variation, when W₁ is a P_(CSIRS)×L, and is not common for twoantenna polarizations, the precoders for v layers are then given by

${W_{\ldots,t,u}^{l} = {\frac{1}{\sqrt{N_{1}N_{2}\gamma_{t,u,l}}}\left\lbrack {\overset{L - 1}{\sum\limits_{i = 0}}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\overset{M_{v} - 1}{\sum\limits_{f = 0}}{\overset{N - 1}{\sum\limits_{d = 0}}{y_{t,u,l}^{(k)}x_{l,i,f,d}}}}}} \right\rbrack}},{l = 1},\ldots,v,$${\gamma_{t,u,l} = {\sum_{i = 0}^{L - 1}{❘{\sum_{f = 0}^{M_{v} - 1}{\sum_{d = 0}^{N - 1}{y_{t,u,l}^{(k)}x_{l,i,f,d}}}}❘}^{2}}},$

Where v_(m) ₁ _((i)) _(,m) ₂ _((i)) is a P_(CSIRS)×1 or 2N₁N₂×1 FD basisvector.

In one example, the same as examples described above except that the SDbasis is replaced with a port selection (PS) basis, i.e., the 2L antennaports vectors are selected from the P_(CSIRS) CSIRS ports. The rest ofthe details are the same as in the examples described above.

In one example, whether there is any selection in SD or not depends onthe value of L. If

${L = \frac{P_{{CSI} - {RS}}}{2}},$

there is no need for any selection in SD (since all ports are selected),and when L

${L < \frac{P_{{CSI} - {RS}}}{2}},$

the SD ports are selected (hence reported), where this selection isaccording to at least one example described above.

In one example, the SD basis is analogous to the W₁ component inRel.15/16 Type II port selection codebook (cf 5.2.2.2.3/5.2.2.2.5, REF8), wherein the L_(l) antenna ports or column vectors of A_(l) areselected by the index

$q_{1} \in \left\{ {0,1,\ldots,{\left\lceil \frac{P_{{CSI} - {RS}}}{2d} \right\rceil - 1}} \right\}$

this requires

$\left\lceil {\log_{2}\left\lceil \frac{P_{{CSI} - {RS}}}{2d} \right\rceil} \right\rceil$

bits), where

$d \leq {{\min\left( {\frac{P_{{CSI} - {RS}}}{2},L_{l}} \right)}.}$

In one example, d∈{1, 2, 3, 4}. To select columns of A_(l), the portselection vectors are used, For instance, a_(i)=v_(m), where thequantity v_(m) is a P_(CSI-RS)/2-element column vector containing avalue of 1 in element m mod P_(CSI-RS)/2 and zeros elsewhere (where thefirst element is element 0). The port selection matrix is then given by

$W_{1} = {A_{l} = {{\begin{bmatrix}X & 0 \\0 & X\end{bmatrix}{where}X} = {\begin{bmatrix}v_{{q}_{1}d} & v_{{{q}_{1}d} + 1} & \cdots & v_{{q_{1}d} + L_{l} - 1}\end{bmatrix}.}}}$

The SD basis is selected either common (the same) for the two antennapolarizations or independently for each of the two antennapolarizations.

In one example, the SD basis selects L_(l) antenna ports freely, i.e.,the L_(l) antenna ports per polarization or column vectors of A_(l) areselected freely by the index

$q_{1} \in \left\{ {0,1,\ldots,{\begin{pmatrix}\frac{P_{{CSI} - {RS}}}{2} \\L_{l}\end{pmatrix} - 1}} \right\}$

this requires

$\left. {\left\lceil {\log_{2}\begin{pmatrix}\frac{P_{{CSI} - {RS}}}{2} \\L_{l}\end{pmatrix}} \right\rceil{bits}} \right).$

To select columns of A&, the port selection vectors are used, Forinstance, a_(i)=v_(m), where the quantity v_(m) is aP_(CSI-RS)/2-element column vector containing a value of 1 in element (mmod P_(CSI-RS)/2) and zeros elsewhere (where the first element iselement 0). Let {x₀, x₁, . . . , x_(L) _(l) ₋₁} be indices of selectionvectors selected by the index q₁. The port selection matrix is thengiven by

$W_{1} = {A_{l} = {{\begin{bmatrix}X & 0 \\0 & X\end{bmatrix}{where}X} = {\begin{bmatrix}v_{x_{0}} & v_{x_{1}} & \cdots & v_{x_{L_{l} - 1}}\end{bmatrix}.}}}$

The SD basis is selected either common (the same) for the two antennapolarizations or independently for each of the two antennapolarizations.

In one example, the SD basis selects L_(l) antenna ports freely fromP_(CSI-RS) ports, i.e., the L_(l) antenna ports or column vectors ofA_(l) are selected freely by the index

$q_{1} \in \left\{ {0,1,\ldots,{\begin{pmatrix}P_{{CSI} - {RS}} \\L_{l}\end{pmatrix} - 1}} \right\}$

(this requires

$\left. {\left\lceil {\log_{2}\begin{pmatrix}P_{{CSI} - {RS}} \\L_{l}\end{pmatrix}} \right\rceil{bits}} \right).$

To select columns of A_(l), the port selection vectors are used, Forinstance, a_(i)=v_(m), where the quantity v_(m) is a P_(CSI-RS)-elementcolumn vector containing a value of 1 in element (m mod P_(CSI-RS)) andzeros elsewhere (where the first element is element 0). Let {x₀, x₁, . .. , x_(L) _(l) ₋₁} be indices of selection vectors selected by the indexq₁. The port selection matrix is then given by

$W_{1} = {A_{l} = {{\begin{bmatrix}X & 0 \\0 & X\end{bmatrix}{where}X} = {\begin{bmatrix}v_{x_{0}} & v_{x_{1}} & \cdots & v_{x_{L_{l} - 1}}\end{bmatrix}.}}}$

In one example, the SD basis selects 2L₁ antenna ports freely fromP_(CSI-RS) ports, i.e., the 2L₁ antenna ports or column vectors of A₁are selected freely by the index

q₁∈

(this requires

$\left. {\left\lceil {\log_{2}\begin{pmatrix}P_{{CSI} - {RS}} \\{2L_{l}}\end{pmatrix}} \right\rceil{bits}} \right).$

To select columns of A_(l), the port selection vectors are used, Forinstance, a_(i)=v_(m), where the quantity v_(m) is a P_(CSI-RS)-elementcolumn vector containing a value of 1 in element (m mod P_(CSI-RS)) andzeros elsewhere (where the first element is element 0). Let {x₀, x₁, . .. , x_(2L) _(l) ₋₁} be indices of selection vectors selected by theindex q₁. The port selection matrix is then given by

$W_{1} = {A_{l} = {{\begin{bmatrix}X & 0 \\0 & X\end{bmatrix}{where}X} = {\begin{bmatrix}v_{x_{0}} & v_{x_{1}} & \cdots & v_{x_{{2L_{l}} - 1}}\end{bmatrix}.}}}$

In one embodiment, which is an extension of an embodiment describedabove, wherein the UE is configured to report a CSI determined based ona codebook comprising components: (A) two separate basis matrices W₁,W_(f), for SD, FD compression, (B) for each (SD,FD) basis vector pairswith indices (i,f), an independent/separate TD/DD basis matrix W_(d)^((i,f)) for DD or TD compression, and (C) coefficients {tilde over(W)}₂. In particular, the precoder for layer l is given by

$W_{l}\begin{bmatrix}{\overset{L - 1}{\sum\limits_{i = 0}}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\overset{M_{v} - 1}{\sum\limits_{f = 0}}{\overset{N - 1}{\sum\limits_{d = 0}}{c_{l,i,f,d}\left( {g_{f,l} \otimes h_{d,l}^{({i,f})}} \right)}^{H}}}}} \\{\overset{L - 1}{\sum\limits_{i = 0}}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\overset{M_{v} - 1}{\sum\limits_{f = 0}}{\overset{N - 1}{\sum\limits_{d = 0}}{c_{l,{i + L},f,d}\left( {g_{f,l} \otimes h_{d,l}^{({i,f})}} \right)}^{H}}}}}\end{bmatrix}$

Where g_(f,l)⊗h_(d,l) ^((i)) is Kronecker product (KP) of FD and TD/DDbasis vectors g_(f,l) and h_(d,l) ^((i,f)). Here, the set of TD/DD basisvectors {h_(d,l) ^((i,f))} for each (SD,FD) basis vector pairs (v_(m) ₁_((i)) _(,m) ₂ _((i)) , g_(f,l)) is polarization-common, i.e., thesame/common set of TD/DD basis vectors are determined/reported for thetwo antenna polarizations, a first polarization and second polarization.In one example, the first polarization comprises a first group CSI-RSantenna ports

$\left\{ {x,{x + 1},{{\ldots x} + \frac{P_{CSIRS}}{2} - 1}} \right\},$

and the second polarization comprises a second group CSI-RS antennaports

$\left\{ {{x + \frac{P_{CSIRS}}{2}},{x + \frac{P_{CSIRS}}{2} + 1},{{\ldots x} + P_{CSIRS} - 1}} \right\}$

and x is the index of the first CSI-RS antenna port. So, the number ofsets of TD/DD basis vectors is LM_(v) (when the sets are the same forall layers) or LM_(v)v (when the sets can be different for v layers).

The N DD/TD basis vectors, h_(d,l) ^((i,f))=[ϕ_(0,l) ^((i,f,d)) ϕ_(1,l)^((i,f,d)) . . . ϕ_(N) ₄ _(-1,l) ^((i,f,d))], d=0, 1, . . . , N−1, areidentified by n_(4,l) (l=1, . . . , v) where

n _(4,l) ={n _(4,l) ^((i,f)) :i=0, . . . ,L−1,f=0, . . . ,M _(v)−1}

n _(4,l) ^((i,f))=[n _(4,l) ⁽⁰⁾ , . . . ,n _(4,l) ^((N-1))]

n _(4,l) ^((d))∈{0,1, . . . ,N ₄−1}

The vector ϕ_(u,l) ^((i,f))=[ϕ_(u,l) ^((i,f,0)) ϕ_(u,l) ^((i,f,1)) . . .ϕ_(u,l) ^((i,f,N-1))] comprises entries of DD/TD basis vectors withDD/TD index u={0, 1, . . . , N₄−1}, which is an (DD/TD) index associatedwith the precoding matrix. The rest of the details can be the same asembodiment I.1. In particular, the precoders for v layers are then givenby

${W_{\ldots,t,u}^{l} = {\frac{1}{\sqrt{N_{1}N_{2}\gamma_{t,u,l}}}\begin{bmatrix}{\overset{L - 1}{\sum\limits_{i = 0}}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\overset{M_{v} - 1}{\sum\limits_{f = 0}}{\overset{N - 1}{\sum\limits_{d = 0}}{y_{t,l}^{(f)}\phi_{u,l}^{({i,f,d})}x_{l,i,f,d}}}}}} \\{\overset{L - 1}{\sum\limits_{i = 0}}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\overset{M_{v} - 1}{\sum\limits_{f = 0}}{\overset{N - 1}{\sum\limits_{d = 0}}{y_{t,l}^{(f)}\phi_{u,l}^{({i,f,d})}x_{l,{i + L},f,d}}}}}}\end{bmatrix}}},{l = 1},\ldots,v,$${\gamma_{t,u,l} = {{\sum_{i = 0}^{L - 1}{❘{\sum_{f = 0}^{M_{v} - 1}{\sum_{d = 0}^{N - 1}{y_{t,l}^{(f)}\phi_{u,l}^{({i,f,d})}x_{l,i,f,d}}}}❘}^{2}} + {\sum_{i = 0}^{L - 1}{❘{\sum_{f = 0}^{M_{v} - 1}{\sum_{d = 0}^{N - 1}{y_{t,l}^{(f)}\phi_{u,l}^{({i,f,d})}x_{l,{i + L},f,d}}}}❘}^{2}}}},$

where x_(l,i,f,d,) is the coefficient (an element of {tilde over (W)}₂)associated with codebook indices (l, i, f, d), where i is a row index of{tilde over (W)}₂ and (f, d) determine the column index k of {tilde over(W)}₂.

In one example, f=k mod M_(v) and

${d = \frac{k - f}{M_{v}}},$

where k∈{0, 1, . . . , M_(v)N} is a column index of {tilde over (W)}₂.Here, k=M_(v)d+f.

In one example, d=k mod N and

$f = {\frac{k - d}{N}.}$

Here, k=Nf+d.

In one example,

$x_{l,i,f,d} = {p_{l,{\lfloor\frac{i}{L}\rfloor}}^{(1)}p_{l,i,f,d}^{(2)}\varphi_{l,i,f,d}}$

similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF8).

In one embodiment, which is an extension of an embodiment describedabove, wherein the UE is configured to report a CSI determined based ona codebook comprising components: (A) two separate basis matrices W₁,W_(f), for SD, FD compression, (B) for each (SD,FD) basis vector pairswith indices (i,f), an independent/separate TD/DD basis matrix W_(d)^((i,f)) for DD or TD compression, and (C) coefficients {tilde over(W)}₂. In particular, the precoder for layer l is given by

$W_{l} = \begin{bmatrix}{\overset{L - 1}{\sum\limits_{i = 0}}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\overset{M_{v} - 1}{\sum\limits_{f = 0}}{\overset{N - 1}{\sum\limits_{d = 0}}{c_{l,i,f,d}\left( {g_{f,l} \otimes h_{d,l}^{({i,f})}} \right)}^{H}}}}} \\{\overset{L - 1}{\sum\limits_{i = 0}}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\overset{M_{v} - 1}{\sum\limits_{f = 0}}{\overset{N - 1}{\sum\limits_{d = 0}}{c_{l,{i + L},f,d}\left( {g_{f,l} \otimes h_{d,l}^{({{i + L},f})}} \right)}^{H}}}}}\end{bmatrix}$

where g_(f,l)⊗h_(d,l) ^((i)) is Kronecker product (KP) of FD and TD/DDbasis vectors g_(f,l) and h_(d,l) ^((i,f)). Here, the set of TD/DD basisvectors {h_(d,l) ^((i,f))} for each (SD,FD) basis vector pairs (v_(m) ₁_((i)) _(,m) ₂ _((i)) ,g_(f,l)) is polarization-specific orpolarization-independent, i.e., the set of TD/DD basis vectors aredetermined/reported for each polarizations. So, the number of sets ofTD/DD basis vectors is 2LM (when the sets are the same for all layers)or 2LM_(v)v (when the sets can be different for v layers).

The N DD/TD basis vectors, h_(d,l) ^((i,f))=[ϕ_(0,l) ^((i,f,d)) ϕ_(1,l)^((i,f,d)) . . . ϕ_(N) ₄ _(-1,l) ^((i,f,d))], d=0, 1, . . . , N−1, areidentified by n_(4,l) (l=1, . . . , v) where

n _(4,l) ={n _(4,l) ^((i,f)) :i=0, . . . ,2L−1,f=0, . . . ,M _(v)−1}

n _(4,l) ^((i,f))=[n _(4,l) ⁽⁰⁾ , . . . ,n _(4,l) ^((N-1))]

n _(4,l) ^((d))∈{0,1, . . . ,N ₄−1}

The vector ϕ_(u,l) ^((i,f))=[ϕ_(u,l) ^((i,f,0)) ϕ_(u,l) ^((i,f,1)) . . .ϕ_(u,l) ^((i,f,N-1))] comprises entries of DD/TD basis vectors withDD/TD index u={0, 1, . . . , N₄−1}, which is an (DD/TD) index associatedwith the precoding matrix. The rest of the details can be the same asembodiment I.1. In particular, the precoders for v layers are then givenby

${W_{\ldots,t,u}^{l} = {\frac{1}{\sqrt{N_{1}N_{2}\gamma_{t,u,l}}}\begin{bmatrix}{\overset{L - 1}{\sum\limits_{i = 0}}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\overset{M_{v} - 1}{\sum\limits_{f = 0}}{\overset{N - 1}{\sum\limits_{d = 0}}{y_{t,l}^{(f)}\phi_{u,l}^{({i,f,d})}x_{l,i,f,d}}}}}} \\{\overset{L - 1}{\sum\limits_{i = 0}}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\overset{M_{v} - 1}{\sum\limits_{f = 0}}{\overset{N - 1}{\sum\limits_{d = 0}}{y_{t,l}^{(f)}\phi_{u,l}^{({{i + L},f,d})}x_{l,{i + L},f,d}}}}}}\end{bmatrix}}},{l = 1},\ldots,v,$${\gamma_{t,u,l} = {\sum_{i = 0}^{{2L} - 1}{❘{\sum_{f = 0}^{M_{v} - 1}{\sum_{d = 0}^{N - 1}{y_{t,l}^{(f)}\phi_{u,l}^{({i,f,d})}x_{l,i,f,d}}}}❘}^{2}}},$

where x_(l,i,f,d) is the coefficient (an element of {tilde over (W)}₂)associated with codebook indices (l, i, f, d), where i is a row index of{tilde over (W)}₂ and (f, d) determine the column index k of {tilde over(W)}₂.

In one example, f=k mod M_(v) and

${d = \frac{k - f}{M_{v}}},$

where k∈{0, 1, . . . , M_(v)N} is a column index of {tilde over (W)}₂.Here, k=M_(v)d+f.

In one example, d=k mod N and

$f = {\frac{k - d}{N}.}$

Here, k=Nf+d.

In one example,

$x_{l,i,f,d} = {p_{l,{\lfloor\frac{i}{L}\rfloor}}^{(1)}p_{l,i,f,d}^{(2)}\varphi_{l,i,f,d}}$

similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF8).

In one embodiment, which is an extension of an embodiment describedabove, wherein the UE is configured to report a CSI determined based ona codebook comprising components: (A) two separate basis matrices W₁,W_(f), for SD, FD compression, (B) for each SD basis vector with indexi, an independent/separate TD/DD basis matrix W_(d) for DD or TDcompression, and (C) coefficients {tilde over (W)}₂. In particular, theprecoder for layer l is given by

$W_{l}\begin{bmatrix}{\overset{L - 1}{\sum\limits_{i = 0}}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\overset{M_{v} - 1}{\sum\limits_{f = 0}}{\overset{N - 1}{\sum\limits_{d = 0}}{c_{l,i,f,d}\left( {g_{f,l} \otimes h_{d,l}^{(i)}} \right)}^{H}}}}} \\{\overset{L - 1}{\sum\limits_{i = 0}}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\overset{M_{v} - 1}{\sum\limits_{f = 0}}{\overset{N - 1}{\sum\limits_{d = 0}}{c_{l,{i + L},f,d}\left( {g_{f,l} \otimes h_{d,l}^{(i)}} \right)}^{H}}}}}\end{bmatrix}$

Where g_(f,l)⊗h_(d,l) ^((i)) is Kronecker product (KP) of FD and TD/DDbasis vectors g_(f,l) and h_(d,l) ^((i)) Here, the set of TD/DD basisvectors {h_(d,l) ^((i))} for each SD basis vector v_(m) ₁ _((i)) _(,m) ₂_((i)) is polarization-common, i.e., the same/common set of TD/DD basisvectors are determined/reported for the two antenna polarizations, afirst polarization and second polarization. In one example, the firstpolarization comprises a first group CSI-RS antenna ports

$\left\{ {x,{x + 1},{{\ldots x} + \frac{P_{CSIRS}}{2} - 1}} \right\},$

and the second polarization comprises a second group CSI-RS antennaports

$\left\{ {{x + \frac{P_{CSIRS}}{2}},{x + \frac{P_{CSIRS}}{2} + 1},{{\ldots x} + P_{CSIRS} - 1}} \right\}$

and x is the index of the first CSI-RS antenna port. So, the number ofsets of TD/DD basis vectors is L (when the sets are the same for alllayers) or Lv (when the sets can be different for v layers).

The N DD/TD basis vectors, h_(d,l) ^((i))=[ϕ_(0,l) ^((i,d)) ϕ_(1,l)^((i,d)) . . . ϕ_(N) ₄ _(-1,l) ^((i,d))], d=0, 1, . . . ,N−1, areidentified by n_(4,l) (l=1, . . . , v) where

n _(4,1) ={n _(4,l) ^((i)) :i=0, . . . ,L−1}

n _(4,l) ^((i))=[n _(4,l) ⁽⁰⁾ , . . . ,n _(4,l) ^((N-1))]

n _(4,l) ^((d))∈{0,1, . . . ,N ₄−1}

The vector ϕ_(u,l) ^((i))=[ϕ_(u,l) ^((i,0)) ϕ_(u,l) ^((i,1)) . . .ϕ_(u,l) ^((i,N-1))] comprises entries of DD/TD basis vectors with DD/TDindex u={0, 1, . . . , N₄−1}, which is an (DD/TD) index associated withthe precoding matrix. The rest of the details can be the same asembodiment I.1. In particular, the precoders for v layers are then givenby

${W_{\ldots,t,u}^{l} = {\frac{1}{\sqrt{N_{1}N_{2}\gamma_{t,u,l}}}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{(f)}\phi_{u,l}^{({i,d})}x_{l,i,f,d}}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{(f)}\phi_{u,l}^{({i,d})}x_{l,{i + L},f,d}}}}}}\end{bmatrix}}},{l = 1},\ldots,\upsilon,$${\gamma_{t,u,l} = {{\sum_{i = 0}^{L - 1}{❘{\sum_{f = 0}^{M_{\upsilon} - 1}{\sum_{d = 0}^{N - 1}{y_{t,l}^{(f)}\phi_{u,l}^{({i,d})}x_{l,i,f,d}}}}❘}^{2}} + {\sum_{i = 0}^{L - 1}{❘{\sum_{f = 0}^{M_{\upsilon} - 1}{\sum_{d = 0}^{N - 1}{y_{t,l}^{(f)}\phi_{u,l}^{({i,d})}x_{l,{i + L},f,d}}}}❘}^{2}}}},$

where x_(l,i,f,d) is the coefficient (an element of {tilde over (W)}₂)associated with codebook indices (l, i, f, d), where i is a row index of{tilde over (W)}₂ and (f, d) determine the column index k of {tilde over(W)}₂.

In one example, f=k mod M_(v) and

${d = \frac{k - f}{M_{\upsilon}}},$

where k∈{0, 1, . . . , M_(v)N} is a column index of {tilde over (W)}₂.Here, k=M_(v)d+f.

In one example, d=k mod N and

$f = {\frac{k - d}{N}.}$

Here, k=Nf+d.

In one example,

$x_{l,i,f,d} = {p_{l,{\lfloor\frac{i}{L}\rfloor}}^{(1)}p_{l,i,f,d}^{(2)}\varphi_{l,i,f,d}}$

similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF8).

In one embodiment, which is an extension of an embodiment describedabove, wherein the UE is configured to report a CSI determined based ona codebook comprising components: (A) two separate basis matrices W₁,W_(f), for SD, FD compression, (B) for each SD basis vector with indexi, an independent/separate TD/DD basis matrix W_(d) for DD or TDcompression, and (C) coefficients {tilde over (W)}₂. In particular, theprecoder for layer l is given by

$W_{l} = \begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{c_{l,i,f,d}\left( {{\mathcal{g}}_{f,l} \otimes h_{d,l}^{(i)}} \right)}^{H}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{c_{l,{i + L},f,d}\left( {{\mathcal{g}}_{f,l} \otimes h_{d,l}^{({i + L})}} \right)}^{H}}}}}\end{bmatrix}$

where g_(f,l)⊗h_(d,l) ^((i)) is Kronecker product (KP) of FD and TD/DDbasis vectors g_(f,l) and h_(d,l) ^((i)). Here, the set of TD/DD basisvectors {h_(d,l) ^((i))} for each SD basis vector v_(m) ₁ _((i)) _(,m) ₂_((i)) is polarization-specific or polarization-independent, i.e., theset of TD/DD basis vectors are determined/reported for eachpolarizations. So, the number of sets of TD/DD basis vectors is 2L (whenthe sets are the same for all layers) or 2Lv (when the sets can bedifferent for v layers).

The N DD/TD basis vectors, h_(d,l) ^((i))=[ϕ_(0,l) ^((i,d)) ϕ_(1,l)^((i,d)) . . . ϕ_(N) ₄ _(-1,l) ^((i,d))], d=0, 1, . . . , N−1, areidentified by n_(4,l) (l=1, . . . , v) where

n _(4,1) ={n _(4,l) ^((i)) :i=0, . . . ,2L−1}

n _(4,l) ^((i))=[n _(4,l) ⁽⁰⁾ , . . . ,n _(4,l) ^((N-1))]

n _(4,l) ^((d))∈{0,1, . . . ,N ₄−1}

The vector ϕ_(u,l) ^((i))=[ϕ_(u,l) ^((i,0)) ϕ_(u,l) ^((i,1)) . . .ϕ_(u,l) ^((i,N-1))] comprises entries of DD/TD basis vectors with DD/TDindex u={0, 1, . . . , N₄−1}, which is an (DD/TD) index associated withthe precoding matrix. The rest of the details can be the same asembodiment I.1. In particular, the precoders for v layers are then givenby

${W_{\ldots,t,u}^{l} = {\frac{1}{\sqrt{N_{1}N_{2}\gamma_{t,u,l}}}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{(f)}\phi_{u,l}^{({i,d})}x_{l,i,f,d}}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{(f)}\phi_{u,l}^{({{i + L},d})}x_{l,{i + L},f,d}}}}}}\end{bmatrix}}},{l = 1},\ldots,\upsilon,$${\gamma_{t,u,l} = {\sum_{i = 0}^{{2L} - 1}{❘{\sum_{f = 0}^{M_{\upsilon} - 1}{\sum_{d = 0}^{N - 1}{y_{t,l}^{(f)}\phi_{u,l}^{({i,d})}x_{l,i,f,d}}}}❘}^{2}}},$

where x_(l,i,f,d) is the coefficient (an element of {tilde over (W)}₂)associated with codebook indices (l, i, f, d), where i is a row index of{tilde over (W)}₂ and (f, d) determine the column index k of {tilde over(W)}₂.

In one example, f=k mod M_(v) and

${d = \frac{k - f}{M_{\upsilon}}},$

where k∈{0, 1, . . . , M_(v)N} is a column index of {tilde over (W)}₂.Here, k=M_(v)d+f.

In one example, d=k mod N and

$f = {\frac{k - d}{N}.}$

Here, k=Nf+d.

In one example,

$x_{l,i,f,d} = {p_{l,{\lfloor\frac{i}{L}\rfloor}}^{(1)}p_{l,i,f,d}^{(2)}\varphi_{l,i,f,d}}$

similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF8).

In one embodiment, which is an extension of an embodiment describedabove, wherein the UE is configured to report a CSI determined based ona codebook comprising components: (A) one SD basis matrix W₁ for SDcompression, (B) for each SD basis vector with index i, anindependent/separate W_(f) for FD compression and anindependent/separate TD/DD basis matrix W_(d) ^((i)) for DD or TDcompression, and (C) coefficients {tilde over (W)}₂. In particular, theprecoder for layer l is given by

$W_{l}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{c_{l,i,f,d}\left( {{\mathcal{g}}_{f,l}^{(i)} \otimes h_{d,l}^{(i)}} \right)}^{H}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{c_{l,{i + L},f,d}\left( {{\mathcal{g}}_{f,l}^{(i)} \otimes h_{d,l}^{(i)}} \right)}^{H}}}}}\end{bmatrix}$

Where g_(f,l) ^((i))⊗h_(d,l) ^((i)) is Kronecker product (KP) of FD andTD/DD basis vectors g_(f,l) ^((i)) and h_(d,l) ^((i)). Here, the set ofFD basis vectors {g_(f,l) ^((i))} and TD/DD basis vectors {h_(d,l)^((i))} for each SD basis vector v_(m) ₁ _((i)) _(,m) ₂ _((i)) ispolarization-common, i.e., the same/common set of FD basis vectors andTD/DD basis vectors are determined/reported for the two antennapolarizations, a first polarization and second polarization. In oneexample, the first polarization comprises a first group CSI-RS antennaports

$\left\{ {x,{x + 1},{{\ldots x} + \frac{P_{CSIRS}}{2} - 1}} \right\},$

and the second polarization comprises a second group CSI-RS antennaports

$\left\{ {{x + \frac{P_{CSIRS}}{2}},{x + \frac{P_{CSIRS}}{2} + 1},{{\ldots x} + P_{CSIRS} - 1}} \right\}$

and x is the index of the first CSI-RS antenna port. So, the number ofsets of FD basis vectors is L (when the sets are the same for alllayers) or Lv (when the sets can be different for v layers). Likewise,the number of sets of TD/DD basis vectors is L (when the sets are thesame for all layers) or Lv (when the sets can be different for vlayers).

The N DD/TD basis vectors, h_(d,l) ^((i))=[ϕ_(0,l) ^((i,d)) ϕ_(1,l)^((i,d)) . . . ϕ_(N) ₄ _(-1,l) ^((i,d))], d=0, 1, . . . , N−1, areidentified by n_(4,l) (l=1, . . . , v) where

n _(4,1) ={n _(4,l) ^((i)) :i=0, . . . ,L−1}

n _(4,l) ^((i))=[n _(4,l) ⁽⁰⁾ , . . . ,n _(4,l) ^((N-1))]

n _(4,l) ^((d))∈{0,1, . . . ,N ₄−1}

The vector ϕ_(u,l) ^((i))=[ϕ_(u,l) ^((i,0)) ϕ_(u,l) ^((i,1)) . . .ϕ_(u,l) ^((i,N-1))] comprises entries of DD/TD basis vectors with DD/TDindex u={0, 1, . . . , N₄−1}, which is an (DD/TD) index associated withthe precoding matrix. The rest of the details can be the same asembodiment I.1. In particular, the precoders for v layers are then givenby

${W_{\ldots,t,u}^{l} = {\frac{1}{\sqrt{N_{1}N_{2}\gamma_{t,u,l}}}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,i,f,d}}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,{i + L},f,d}}}}}}\end{bmatrix}}},{l = 1},\ldots,\upsilon,$${\gamma_{t,u,l} = {{\sum_{i = 0}^{L - 1}{❘{\sum_{f = 0}^{M_{\upsilon} - 1}{\sum_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,i,f,d}}}}❘}^{2}} + {\sum_{i = 0}^{L - 1}{❘{\sum_{f = 0}^{M_{\upsilon} - 1}{\sum_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,{i + L},f,d}}}}❘}^{2}}}},$

where x_(l,i,f,d) is the coefficient (an element of {tilde over (W)}₂)associated with codebook indices (l, i, f, d), where i is a row index of{tilde over (W)}₂ and (f, d) determine the column index k of {tilde over(W)}₂.

In one example, f=k mod M_(v) and

${d = \frac{k - f}{M_{\upsilon}}},$

where k∈{0, 1, . . . , M_(v)N} is a column index of {tilde over (W)}₂.Here, k=M_(v)d+f.

In one example, d=k mod N and

$f = {\frac{k - d}{N}.}$

Here, k=Nf+d.

In one example,

$x_{l,i,f,d} = {p_{l,{\lfloor\frac{i}{L}\rfloor}}^{(1)}p_{l,i,f,d}^{(2)}\varphi_{l,i,f,d}}$

similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF8).

In one embodiment, which is an extension of an embodiment describedabove, wherein the UE is configured to report a CSI determined based ona codebook comprising components: (A) one SD basis matrix W₁ for SDcompression, (B) for each SD basis vector with index i, anindependent/separate W_(f) for FD compression and anindependent/separate TD/DD basis matrix W_(d) ^((i)) for DD or TDcompression, and (C) coefficients {tilde over (W)}₂. In particular, theprecoder for layer l is given by

$W_{l}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{c_{l,i,f,d}\left( {{\mathcal{g}}_{f,l}^{(i)} \otimes h_{d,l}^{(i)}} \right)}^{H}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{c_{l,{i + L},f,d}\left( {{\mathcal{g}}_{f,l}^{({i + L})} \otimes h_{d,l}^{({i + L})}} \right)}^{H}}}}}\end{bmatrix}$

Where g_(f,l)⊗h_(d,l) ^((i)) is Kronecker product (KP) of FD and TD/DDbasis vectors g_(f,l) ^((i)) and h_(d,l) ^((i)). Here, the set of FDbasis vectors {g_(f,l) ^((i))} and TD/DD basis vectors {h_(d,l) ^((i))}for each SD basis vector v_(m) ₁ _((i)) _(,m) ₂ _((i)) ispolarization-specific or polarization-independent, i.e., the set ofTD/DD basis vectors are determined/reported for each polarizations. So,the number of sets of FD basis vectors is 2L (when the sets are the samefor all layers) or 2Lv (when the sets can be different for v layers).Likewise, the number of sets of TD/DD basis vectors is 2L (when the setsare the same for all layers) or 2Lv (when the sets can be different forv layers).

The N DD/TD basis vectors, h_(d,l) ^((i))=[ϕ_(0,l) ^((i,d)) ϕ_(1,l)^((i,d)) . . . ϕ_(N) ₄ _(-1,l) ^((i,d))], d=0, 1, . . . , N−1, areidentified by n_(4,l) (l=1, . . . , v) where

n _(4,1) ={n _(4,l) ^((i)) :i=0, . . . ,2L−1}

n _(4,l) ^((i))=[n _(4,l) ⁽⁰⁾ , . . . ,n _(4,l) ^((N-1))]

n _(4,l) ^((d))∈{0,1, . . . ,N ₄−1}

The vector ϕ_(u,l) ^((i))=[ϕ_(u,l) ^((i,0)) ϕ_(u,l) ^((i,1)) . . .ϕ_(u,l) ^((i,N-1))] comprises entries of DD/TD basis vectors with DD/TDindex u={0, 1, . . . , N₄−1}, which is an (DD/TD) index associated withthe precoding matrix. The rest of the details can be the same asembodiment 1.1. In particular, the precoders for v layers are then givenby

${W_{\ldots,t,u}^{l} = {\frac{1}{\sqrt{N_{1}N_{2}\gamma_{t,u,l}}}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,i,f,d}}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{\upsilon} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{({{i + L},f})}\phi_{u,l}^{({{i + L},d})}x_{l,{i + L},f,d}}}}}}\end{bmatrix}}},{l = 1},\ldots,\upsilon,$${\gamma_{t,u,l} = {\sum_{i = 0}^{{2L} - 1}{❘{\sum_{f = 0}^{M_{\upsilon} - 1}{\sum_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,i,f,d}}}}❘}^{2}}},$

where x_(l,i,f,d) is the coefficient (an element of {tilde over (W)}₂)associated with codebook indices (l, i, f, d), where i is a row index of{tilde over (W)}₂ and (f, d) determine the column index k of {tilde over(W)}₂.

In one example, f=k mod M_(v) and

${d = \frac{k - f}{M_{\upsilon}}},$

where k∈{0, 1, . . . , M_(v)N} is a column index of {tilde over (W)}₂.Here, k=M_(v)d+f.

In one example, d=k mod N and

$f = {\frac{k - d}{N}.}$

Here, k=Nf+d.

In one example,

$x_{l,i,f,d} = {p_{l,{\lfloor\frac{i}{L}\rfloor}}^{(1)}p_{l,i,f,d}^{(2)}\varphi_{l,i,f,d}}$

similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF8).

In one embodiment, the same as one or more embodiments described aboveexcept that the SD basis vectors v_(m) ₁ _((i)) _(,m) ₂ _((i)) arereplaced with port selection (PS) vectors v_(m) _((i)) , i.e., the 2Lantenna ports vectors are selected from the P_(CSIRS) CSIRS ports, e.g.,as in Rel. 16 or 17 Type II port selection codebooks [cf. 5.2.2.2.6 and5.2.2.2.7 of REF 8]. The rest of the details are the same as inembodiment I.1A through I.1D. The details of the port selection vectorsare according to at least one of the examples described above.

In one embodiment, the UE is configured to report a CSI determined basedon a codebook comprising components: (A) two basis matrices, basis W₁for SD, and a joint basis W_(joint) for joint FD and DD/TD compression,and (B) coefficients {tilde over (W)}₂. In particular, the precoder forlayer l is given by

W _(l) =A _(l) C _(l) B _(l) ^(H) =W ₁ {tilde over (W)} ₂ W _(joint)^(H)

Here W₁ is a P_(CSIRS)×N₃N₄ matrix whose columns are precoding vectorsfor a total of N₃N₄ units, N₃ FD units and N₄ DD/TD units, W₁ is aP_(CSIRS)×2L or P_(CSIRS)×L SD basis matrix (similar to Rel. 16 enhancedType II codebook), {tilde over (W)}₂ is a 2L×M_(v) coefficients matrix,and W_(joint) is a N₃N₄×M_(v) basis matrix comprising M_(v) joint (FD,DD/TD) basis vectors. The k-th column of W_(joint) is a vector v_(k,l)that is a KP of two vectors g_(k,l) and h_(k,l), where (g_(k,l),h_(k,l)) is the k-th joint (FD, DD/TD) basis vectors, and k=0, 1, . . ., M_(v)−1.

In one example, v_(k,l)=[g_(k,l)ϕ_(0,l) ^((k)) g_(k,l)(k)ϕ_(1,l) ^((k)). . . g_(k,l)ϕ_(N) ₄ _(-1,l) ^((k))]^(T), the KP of g_(k,l) and h_(k,l).

In one example v_(k,l)=[y_(0,l) ^((k)) y_(1,l) ^((k)) . . . y_(N) ₃_(-1,l) ^((k))]^(T), the KP of g_(k,l) and h_(k,l). Hereg_(k,l)=[u_(0,l) ^((k)) y_(1,l) ^((k)) . . . y_(N) ₃ _(-1,1) ^((k))] andh_(k,l)=[ϕ_(0,l) ^((k)) ϕ_(1,l) ^((k)) . . . ϕ_(N) ₄ _(-1,l) ^((k))].

At least one of the following examples is used/configured regarding thereporting of the two bases.

-   -   In one example, both bases are reported by the UE, e.g., via a        component or more than one component of the PMI.    -   In one example, one of the two bases is reported, and the other        basis is either fixed, or configured (e.g., via RRC, MAC CE, or        DCI).        -   In one example, the reported basis corresponds to the SD            basis, and the other basis corresponds to the joint (FD,            DD/TD) basis.        -   In one example, the reported basis corresponds to the joint            (FD, DD/TD) basis, and the other basis corresponds to the SD            basis.

At least one of the following examples is used/configured regarding thethree basis matrices.

In one example, the SD basis W₁ is as described in one or more examplesdescribed above. The M_(v) joint (FD, DD/TD) basis vectorsv_(k,l)=[y_(0,l) ^((k)) y_(1,l) ^((k)) . . . y_(N) ₃ _(N) ₄ _(-1,l)^((k))], k=0, 1, . . . , M_(v)−1, are determined based on the M_(v) (FD,DD/TD) basis vector pairs, (g_(f,l)(k), h_(d,l)(k)), and are identifiedby n_(joint,l) (l=1, . . . , v) where

n _(joint,l) =n _(joint,l) ⁽⁰⁾ , . . . ,n _(joint,l) ^((M) ^(v) ⁻¹⁾

n _(joint,l) ^((k))∈{0,1, . . . ,N ₃ N ₄−1}

In one example, the M_(v) joint (FD, DD/TD) vectors are reportedjointly, similar to L basis reporting for W₁ (cf. Section 5.2.2.2.3, REF8). For instance, the M_(v) vectors can be identified by the indicesi_(joint,1) and i_(joint,2), where

i _(joint,1)=[q ₃ q ₄]

q ₃∈{0,1, . . . ,O ₃−1}

q ₄∈{0,1, . . . ,O ₄−1}

i_(joint,2)∈{0, 1, . . . , (_(M) _(v) ^(N) ³ ^(N) ⁴ )−1} if all M_(v)vectors are selected, or, i_(joint,2)∈{0, 1, . . . , (_(M) _(v) ₋₁ ^(N)³ ^(N) ⁴ ⁻¹)−1} if M_(v)−1 vectors are selected (e.g., n_(joint,l)^((k))∈{1, . . . , N₃N₄−1}) and one vector is fixed (e.g., n_(joint,l)^((k))=0).

Let n_(joint,l) ^((k)) corresponds (maps) to (n_(3,l) ^((k)),n_(4,l)^((k))).

n _(3,l)=[n _(3,l) ⁽⁰⁾ , . . . ,n _(3,l) ^((M) ^(v) ⁻¹⁾]

n _(4,l)=[n _(4,l) ⁽⁰⁾ , . . . ,n _(4,l) ^((M) ^(v) ⁻¹⁾]

n _(3,l) ^((k))∈{0,1, . . . ,N ₃−1}

n _(4,l) ^((k))∈{0,1, . . . ,N ₄−1}

${C\left( {x,y} \right)} = \left\{ {\begin{matrix}\begin{pmatrix}x \\y\end{pmatrix} & {x \geq y} \\0 & {x < y}\end{matrix}.} \right.$

where the values of C(x, y) are given in Table 5.2.2.2.3-1 (REF 8).

Then the elements of n_(3,l) and n_(4,l) are found from i_(joint,2)using the algorithm:

s⁻¹=0

for k=0, . . . , M_(v)−1

-   -   Find the largest x*∈{M_(v)−1−k, . . . , N₃N₄−1−k} in Table        5.2.2.2.3-1 (REF 8) such that i_(joint,2)−s_(k-1)≥C(x*, M_(v)−k)

e_(k) = C(x^(*), M_(υ) − k) s_(k) = s_(k − 1) + e_(k)n^((k)) = N₃N₄ − 1 − x^(*) n₃^((k)) = n^((k))modN₃$n_{4}^{(k)} = \frac{\left( {n^{(k)} - n_{3}^{(k)}} \right)}{N_{3}}$

When n_(3,l) and n_(4,l) are known, i_(joint,2) is found using:

-   -   n_(joint) ^((k))=N₃n^((k))+n₃ ^((k)) where the indices k=0, 1, .        . . , M_(v)−1 are assigned such that n_(joint,l) ^((k))        increases as k increases i_(joint,2)=C(N₃N₄−1−n_(joint,l)        ^((k)), M_(v)−k), where C(x, y) is given in Table 5.2.2.2.3-1        (REF 8).

The vector y_(t,l)=[y_(t,l) ⁽⁰⁾ y_(t,l) ⁽¹⁾ . . . y_(t,l) ^((M) ^(v)⁻¹⁾] comprises entries of joint (FD, DD/TD) basis vectors with indext={0, 1, . . . , N₃N₄−1}, which is a joint (FD, DD/TD) index associatedwith the precoding matrix.

In one example, the joint (FD, DD/TD) basis vectors are orthogonal DFTvectors, and v_(t,l) ^((k))=y_(t) ₁ _(,l) ^((k))ϕ_(t) ₂ _(,l) ^((k))where

${y_{t_{1},l}^{(k)} = {{e^{j\frac{2\pi t_{1}n_{3,l}^{(k)}}{N_{3}}}{and}\phi_{t_{2},l}^{(k)}} = e^{j\frac{2\pi t_{2}n_{4,l}^{(k)}}{N_{4}}}}},$

(t₁,t₂) is determined based on t and vice versa as:

-   -   In one example, t₁=t mod N₃ and

${t_{2} = \frac{t - t_{1}}{N_{3}}},$

-   -    where t∈{0, 1, . . . , N₃N₄}. Here, t=N₃t₂+t₁.    -   In one example, t₂=t mod N₄ and

$t_{1} = {\frac{t - t_{2}}{N_{4}}.}$

-   -    Here, t=N₄t₁+t₂.

In one example, the joint (FD, DD/TD) basis vectors are oversampled (orrotated) orthogonal DFT vectors with the oversampling (rotation) factorO₃ and O₄, and

${y_{t_{1},l}^{(k)} = {{e^{j\frac{2\pi t_{1}n_{3,l}^{(k)}}{O_{3}N_{3}}}{and}\phi_{t_{2},l}^{(k)}} = e^{j\frac{2\pi t_{2}n_{4,l}^{(k)}}{O_{4}N_{4}}}}},$

and the M_(v) joint (FD, DD/TD) basis vectors are also identified by therotation indices q_(3,l)∈{0, 1, . . . , O₃−1} and q_(4,l)∈{0, 1, . . . ,O₄−1}. In one example, O₃ is fixed (e.g., 4), or configured (e.g., viaRRC), or reported by the UE. In one example, O₄ is fixed (e.g., 4), orconfigured (e.g., via RRC), or reported by the UE. In one example, therotation factor is layer-common (one value for all layers), i.e.,q_(3,l)=q₃ or q_(4,l)=q₄.

The precoders for v layers are then given by

${W_{\ldots,t}^{l} = {\frac{1}{\sqrt{N_{1}N_{2}\gamma_{t,l}}}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{k = 0}^{M_{\upsilon} - 1}{y_{t,l}^{(f)}x_{l,i,k}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{k = 0}^{M_{\upsilon} - 1}{y_{t,l}^{(f)}x_{l,{i + L},k}}}}}\end{bmatrix}}},{l = 1},\ldots,\upsilon,$${\gamma_{t,l} = {\sum_{i = 0}^{{2L} - 1}{❘{\sum_{k = 0}^{M_{\upsilon} - 1}{y_{t,l}^{(k)}x_{l,i,k}}}❘}^{2}}},$

where x_(l,i,k) is the coefficient (an element of {tilde over (W)}₂)associated with codebook indices (l, i, k), where i is a row index of{tilde over (W)}₂ and k is the column index of {tilde over (W)}₂.

In one example,

$x_{l,i,k} = {p_{l,{\lfloor\frac{i}{L}\rfloor}}^{(1)}p_{l,i,k}^{(2)}\varphi_{l,i,k}}$

similar to Rel. 16 enhanced Type II codebook (cf. Section 5.2.2.2.5, REF8). Then,

${W_{\ldots,t}^{l} = {\frac{1}{\sqrt{N_{1}N_{2}\gamma_{t,l}}}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}p_{l,0}^{(1)}{\sum\limits_{k = 0}^{M_{v} - 1}{y_{t,l}^{(k)}p_{l,i,k}^{(2)}\varphi_{l,i,k}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}p_{l,1}^{(1)}{\sum\limits_{k = 0}^{M_{v} - 1}{y_{t,l}^{(k)}p_{l,{i + L},k}^{(2)}\varphi_{l,{i + L},k}}}}}\end{bmatrix}}},{l = 1},\ldots,v,$${\gamma_{t,l} = {\sum_{i = 0}^{{2L} - 1}{\left( p_{l,{\lfloor\frac{i}{L}\rfloor}}^{(1)} \right)^{2}{❘{\sum_{k = 0}^{M_{v} - 1}{y_{t,l}^{(k)}p_{l,i,k}^{(2)}\varphi_{l,{ik}}}}❘}^{2}}}},$

and the quantities ϕ_(l,i,k) and p_(l,0) ⁽¹⁾, p_(l,1) ⁽¹⁾, p_(l,i,k) ⁽²⁾correspond to φ_(l,i,f) and p_(l,0) ⁽¹⁾, p_(l,1) ⁽¹⁾, p_(l,i,f) ⁽²⁾,respectively, as described in 5.2.2.2.5 of [REF 8].

In a variation, when W₁ is a P_(CSIRS)×L, and is not common for twoantenna polarizations, the precoders for v layers are then given by

${W_{\ldots,t}^{l} = {\frac{1}{\sqrt{N_{1}N_{2}\gamma_{t,l}}}\left\lbrack {\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{k = 0}^{M_{v} - 1}{y_{t,l}^{(k)}x_{l,i,k}}}}} \right\rbrack}},{l = 1},\ldots,v,$${\gamma_{t,l} = {\sum_{i = 0}^{L - 1}{❘{\sum_{k = 0}^{M_{v} - 1}{y_{t,l}^{(k)}x_{l,{ik}}}}❘}^{2}}},$

Where v_(m) ₁ _((i)) _(,m) ₂ _((i)) is a P_(CSIRS)×1 or 2N₁N₂×1 FD basisvector.

In one example, the same as one or more examples described above exceptthat the SD basis is replaced with a port selection (PS) basis, i.e.,the 2L antenna ports vectors are selected from the P_(CSIRS) CSIRSports. The rest of the details about the PS are the same as in one ormore examples described above.

In one embodiment, the UE is configured to report a CSI determined basedon a codebook comprising components: (A) two basis matrices, basis W₁for SD, and a joint basis W_(joint) for joint FD and DD/TD compression,and (B) coefficients {tilde over (W)}₂. In particular, the precoder forlayer l is given by

W _(l) =A _(l) C _(l) B _(l) ^(H) =W ₁ {tilde over (W)} ₂ W _(joint)^(H)

Here W₁ is a P_(CSIRS)×N₃N₄ matrix whose columns are precoding vectorsfor a total of N₃N₄ units, N₃ FD units and N₄ DD/TD units, W₁ is aP_(CSIRS)×2L or P_(CSIRS)×L SD basis matrix (similar to Rel. 16 enhancedType II codebook), {tilde over (W)}₂ is a 2L×M_(v) coefficients matrix,and W_(joint) is a N₃N₄×M_(v) basis matrix comprising M_(v) joint (FD,DD/TD) basis vectors. The k-th column of W_(joint) is a vector v_(k,i)whose length is N₃N₄, and which is the k-th joint (FD, DD/TD) basisvectors, and k=0, 1, . . . , M_(v)−1.

In one example, v_(k,l)=[m_(0,l), m_(1,l), m_(N) ₃ _(N) ₄ _(,l)]^(T).

In one example, v_(k,l) is the k-th DFT vector on length N₃N₄, i.e.

$v_{k,l} = {{\left\lbrack {1,e^{j\frac{2\pi{k.1}}{N_{3}N_{4}}},e^{j\frac{2\pi{k.2}}{N_{3}N_{4}}},\ldots,e^{j\frac{2\pi{k.{({{N_{3}N_{4}} - 1})}}}{N_{3}N_{4}}}} \right\rbrack{and}m_{x,l}} = {e^{j\frac{2\pi{k.x}}{N_{3}N_{4}}}.}}$

In one example, v_(k,l) is the k-th oversampled DFT vector on lengthN₃N₄, i.e.,

$v_{k,l} = {{\left\lbrack {1,e^{j\frac{2\pi{k.1}}{ON_{3}N_{4}}},e^{j\frac{2\pi{k.2}}{ON_{3}N_{4}}},\ldots,e^{j\frac{2\pi{k.{({{N_{3}N_{4}} - 1})}}}{N_{3}N_{4}}}} \right\rbrack{and}m_{x,l}} = {e^{j\frac{2\pi{k.x}}{N_{3}N_{4}}}.}}$

Here, O is the oversampling factor. In one example, O is fixed (e.g.,4). In one example, O is configured (e.g., via RRC).

In one embodiment, the UE is configured to report a CSI determined basedon a codebook comprising components: (A) two basis matrices, basisW_(d,1) or W_(1,d) for joint SD and DD/TD compression, and a basis W_(f)for FD compression, and (B) coefficients {tilde over (W)}₂. Inparticular, the precoder for layer l is given by

W _(l) =A _(l) C _(l) B _(l) ^(H) =W _(d,1) {tilde over (W)} ₂ W _(f)^(H) or W _(1,d) {tilde over (W)} ₂ W _(f) ^(H)

Here W₁ is a P_(CSIRS)N₄×N₃ matrix whose each column (f) comprisesprecoding vectors for N₄ DD/TD units and a given FD unit f, W₁ is aP_(CSIRS)×2L or P_(CSIRS)×L SD basis matrix (similar to Rel. 16 enhancedType II codebook), W_(f) is a N₃×M_(v) FD basis matrix (similar to Rel.16 enhanced Type II codebook) and W_(d) is a N₄×N DD/TD basis matrix.The columns of W_(d), comprises vectors v_(d,1,l) that are Kroneckerproducts (KPs) of vectors e_(1,l) and h_(d,l), columns of W₁ and W_(d),respectively, i.e., W_(d), =kron(W_(d),W₁), is (P_(CSIRS)N₄)×(2LN). Thecolumns of W_(1,d) comprises vectors v_(1,d,l) that are Kroneckerproducts (KPs) of vectors h_(d,l) and e_(1,l), columns of W_(d) and W₁,respectively, i.e., W_(1,d)=kron(W₁,W_(d)), is (P_(CSIRS)N₄)×(2LN). The{tilde over (W)}₂ is (2LN)×(M_(v)) coefficient matrix.

For FD unit n₃∈{1, . . . , N₃} and DD/TD unit n₄∈{1, . . . , N₄}, theprecoder for layer l is given by

-   -   W_(i)(I,n₃) when W_(l)=W_(d,1){tilde over (W)}₂W_(f), where        I={(n₄−1)*P_(CSIRS)+i:I=1, . . . , P_(CSIRS)} or    -   W_(i)(J,n₃) when W_(i)=W_(1,d){tilde over (W)}₂W_(f) ^(H), where        J={n₄+i×P_(CSIRS)=1, . . . , P_(CSIRS)}.

In one embodiment, the UE is configured to report a CSI determined basedon a codebook comprising components: (A) two basis matrices, basisW_(f,1) or W_(1,f) for joint SD and FD compression, and a basis W_(d)for DD/TD compression, and (B) coefficients {tilde over (W)}₂. Inparticular, the precoder for layer l is given by

W _(l) =A _(l) C _(l) B _(l) ^(H) =W _(f,1) {tilde over (W)} ₂ W _(d)^(H) or W _(1,f) {tilde over (W)} ₂ W _(d) ^(H)

Here W_(l) is a P_(CSIRS)N₃×N₄ matrix whose each column (d) comprisesprecoding vectors for N₃ FD units and a given DD/TD unit d, W₁ is aP_(CSIRS)×2L or P_(CSIRS)×L SD basis matrix (similar to Rel. 16 enhancedType II codebook), W_(f) is a N₃×M_(v) FD basis matrix (similar to Rel.16 enhanced Type II codebook) and W_(d) is a N₄×N DD/TD basis matrix.The columns of W_(f,1) comprises vectors v_(f,1,l) that are Kroneckerproducts (KPs) of vectors e_(1,1) and g_(f,l) columns of W₁ and W_(f),respectively, i.e., W_(f,1)=kron(W_(f),W₁), is (P_(CSIRS)N₃)×(2LM_(v)).The columns of W_(1,f) comprises vectors v_(1,f,l) that are Kroneckerproducts (KPs) of vectors g_(f,l) and e_(1,l), columns of W_(f) and W₁,respectively, i.e., W_(1,f)=kron(W₁,W_(f)), is (P_(CSIRS)N₃)×(2LM_(v)).The {tilde over (W)}₂ is (2LM_(v))×(N) coefficient matrix.

For FD unit n₃∈{1, . . . , N₃} and DD/TD unit n₄∈{1, . . . , N₄}, theprecoder for layer l is given by

-   -   W_(l)(I:,n₄) when W_(l)=W_(f,1){tilde over (W)}₂W_(d) ^(H),        where I={(n₃−1)*P_(CSIRS)+i: i 1, . . . , P_(CSIRS)} or    -   W_(l))(J,n₄) when W_(l)=W_(1,f){tilde over (W)}₂W_(d) ^(H),        where J={n₃+i×P_(CSIRS): i=P_(CSIRS)}.

In one embodiment, the UE is configured to report a CSI determined basedon a codebook comprising components: (A) three separate basis matricesW₁, W_(f), and W_(d) for SD, FD, and DD/TD compression, respectively,and (B) coefficients {tilde over (W)}₂. The details of the componentsare as explained in embodiment 1.1 except that only 2 out of the 3 basismatrices are used for dimension reduction or compression, and the thirdbasis is either fixed (e.g., 1 or identity matrix) or turned OFF (e.g.,via explicit or implicit higher layer or MAC CE or DCI basedsignalling).

For all the components associated with the 3^(rd) dimension, the CSI (orPMI) reporting can correspond to only one value (similar to WB PMIreporting format) or multiple values (similar to SB PMI reportingformat). In one example, this reporting is fixed (e.g., to one value) orconfigurable (e.g., via RRC) or reported by the UE (e.g., as part of UEcapability or CSI reporting).

Also, the component W₁ can correspond to regular (e.g., DFT basedsimilar to Rel. enhanced Type II codebook) or port selection (e.g.,similar to Rel. 16 enhanced port selection Type II codebook).

In one example, the 2 bases used for dimension reduction or compressioncorrespond to SD and FD bases, and the 3^(rd) basis corresponds to theDD/TD basis. The precoder for layer l is given by W_(l)=A_(l)C_(l)B_(l)^(H)=W₁{tilde over (W)}₂W_(f,d) ^(H) (with W_(d)) where W_(d) is fixed(e.g., to 1 or an identity matrix). Alternatively, W_(l)=W₁{tilde over(W)}₂W_(f) ^(H) (without W_(d)).

In one example, the 2 bases used for dimension reduction or compressioncorrespond to SD and DD/TD bases, and the 3^(rd) basis corresponds tothe FD basis. The precoder for layer l is given by W₁=A_(l)C_(l)B_(l)^(H)=W₁{tilde over (W)}₂W_(d) (with W_(f)) where W_(f) is fixed (e.g.,to 1 or an identity matrix). Alternatively, W_(l)=W₁{tilde over(W)}₂W_(d) (without W_(f)).

In one example, the 2 bases used for dimension reduction or compressioncorrespond to FD and DD/TD bases, and the 3^(rd) basis corresponds tothe SD basis. The precoder for layer l is given by W₁=A_(l)C_(l)B_(l)^(H)=W₁{tilde over (W)}₂W_(f,d) ^(H) (with W₁) where W₁ is fixed (e.g.,to 1 or an identity matrix). Alternatively, W_(l)={tilde over (W)}₂W_(f)^(H) (without W₁).

In one embodiment, the UE is configured to report a CSI determined basedon a codebook comprising components: (A) two basis matrices, basis W₁for SD, and a joint basis W_(joint) for joint FD and DD/TD compression,and (B) coefficients {tilde over (W)}₂. The details of the componentsare as explained above except that only W_(joint) is used for dimensionreduction or compression, and the W₁ basis is either fixed (e.g., 1 oridentity matrix) or turned OFF (e.g., via explicit or implicit higherlayer or MAC CE or DCI based signalling).

The precoder for layer l is given by W_(l)=A_(l)C_(l)B_(l) ^(H)=W₁{tildeover (W)}₂W_(joint) ^(H) (with W₁) where W_(d) is fixed (e.g., to 1 oran identity matrix). Alternatively, W_(l)={tilde over (W)}₂W_(joint)^(H) (without W₁).

In one embodiment, the UE is configured to report a CSI determined basedon a codebook comprising components: (A) three separate basis matricesW₁, W_(f), and W_(d) for SD, FD, and DD/TD compression, respectively,and (B) coefficients {tilde over (W)}₂. The details of the componentsare as explained in embodiment 1.1 except that only 1 out of the 3 basismatrices is used for dimension reduction or compression, and one or bothof the other two bases is either fixed (e.g., 1 or identity matrix) orturned OFF (e.g., via explicit or implicit higher layer or MAC CE or DCIbased signalling).

For all the components associated with the other two dimensions, the CSI(or PMI) reporting can correspond to only one value (similar to WB PMIreporting format) or multiple values (similar to SB PMI reportingformat). In one example, this reporting is fixed (e.g., to one value) orconfigurable (e.g., via RRC) or reported by the UE (e.g., as part of UEcapability or CSI reporting).

Also, the component W₁ can correspond to regular (e.g., DFT basedsimilar to Rel. enhanced Type II codebook) or port selection (e.g.,similar to Rel. 16 enhanced port selection Type II codebook).

In one example, the one basis used for dimension reduction orcompression corresponds to SD, and the other two bases correspond to theFD and DD/TD basis. The precoder for layer l is given byW_(l)=A_(l)C_(l)B_(l) ^(H)=W₁{tilde over (W)}₂W_(f,d) ^(H) (with W_(f)and W_(d)) where W_(f) and W_(d) are fixed (e.g., to 1 or an identitymatrix). Alternatively, W_(l)=W₁{tilde over (W)}₂ (without W_(f) andW_(d)).

In one example, the one basis used for dimension reduction orcompression corresponds to FD, and the other two bases correspond to theSD and DD/TD basis. The precoder for layer l is given byW_(l)=A_(l)C_(l)B_(l) ^(H)=W₁{tilde over (W)}₂W_(f,d) ^(H) (with W₁ andW_(d)) where W₁ and W_(d) are fixed (e.g., to 1 or an identity matrix).Alternatively, W_(l)={tilde over (W)}₂W_(f) ^(H) (without W₁ and W_(d)).

In one example, the one basis used for dimension reduction orcompression corresponds to DD/TD, and the other two bases correspond tothe SD and FD basis. The precoder for layer l is given byW_(l)=A_(l)C_(l)B_(l) ^(H)=W₁{tilde over (W)}₂W_(f,d) ^(H) (with W₁ andW_(f)) where W₁ and W_(f) are fixed (e.g., to 1 or an identity matrix).Alternatively, W_(l)={tilde over (W)}₂W_(d) (without W₁ and W_(d)).

Any of the above variation embodiments can be utilized independently orin combination with at least one other variation embodiment.

FIG. 16 illustrates a flow chart of a method 1600 for operating a UE, asmay be performed by a UE such as UE 116, according to embodiments of thepresent disclosure. The embodiment of the method 1600 illustrated inFIG. 16 is for illustration only. FIG. 16 does not limit the scope ofthis disclosure to any particular implementation.

As illustrated in FIG. 16 , the method 1600 begins at step 1602. In step1602, the UE (e.g., 111-116 as illustrated in FIG. 1 ) receives aconfiguration about a CSI report, the configuration includinginformation about a codebook, the codebook comprising components: (i)sets of basis vectors including a first set of vectors each of lengthP_(CSIRS)×1 for a SD, a second set of vectors each of length N₃×1 for aFD, and a third set of vectors each of length N₄×1 for a DD, and (ii)coefficients associated with each basis vector triple (a_(i), b_(f),c_(d)), a_(t) from the first set, b_(f) from the second set, and c_(d)from the third set.

In step 1604, the UE determines, based on the configuration, thecomponents.

In step 1606, the UE transmits the CSI report including: at least onebasis vector indicator indicating all or a portion of the sets of basisvectors, and at least one coefficient indicator indicating all or aportion of the coefficients, wherein N₃ and N₄ are total number of FDand DD units respectively, and wherein P_(CSIRS) is a number of CSI-RSports configured for the CSI report.

In one embodiment, for each FD unit among the total of N₃ FD units andfor each DD unit among the total of N₄ DD units, a precoding vector oflength P_(CSIRS)×1 for a layer l E {1, . . . , v} is based on: a firstsum over the first set of SD basis vectors, a second sum over the secondset of FD vectors, and a third sum over the third set DD vectors, wherethe precoding vector is given by:

${W^{l} = {\frac{1}{\sqrt{\gamma}}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{v} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,i,f,d}}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{v} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,{i + L},f,d}}}}}}\end{bmatrix}}},$

wherein:

L is a number of basis vectors in the first set,

M_(v) is a number of basis vectors in the second set,

N is a number of basis vectors in the third set,

v_(m) ₁ _((i)) _(,m) ₂ _((i)) is a vector of length

$\frac{P_{CSIRS}}{2} \times 1{{and}\begin{bmatrix}v_{m_{1}^{(i)},m_{2}^{(i)}} \\v_{m_{1}^{(i)},m_{2}^{(i)}}\end{bmatrix}}$

is an i-th SD basis vector in the first set,

y_(t,l) ^((i,f)) is a t-th element of an f-th FD basis vector of lengthN₃×1 in the second set,

ϕ_(u,l) ^((i,d)) is a u-th element of a d-th DD basis vector of lengthN₄×1 in the third set,

γ is a normalization factor, and

v is a number of layers.

In one embodiment, the first and the second sets of basis vectors for SDand FD respectively are independent, and the third set of basis vectorscomprises a set of DD basis vectors {c_(d) ^((i,f))} for each (SD, FD)basis vector pair (a_(i),b_(f)).

In one embodiment, the first and the second sets of basis vectors for SDand FD respectively are independent, and the third set of basis vectorscomprises a set of DD basis vectors {c_(d) ^((i))} for each SD basisvector a_(i).

In one embodiment, the first set of basis vectors for SD is independent,the second set of basis vectors comprises a set of FD basis vectors{b_(f) ^((i))} for each SD basis vector a_(i), and the third set ofbasis vectors comprises a set of DD basis vectors {c_(d) ^((i))} foreach SD basis vector a_(i).

In one embodiment, the first set of basis vectors for SD is independent,and the second and the third sets of basis vectors comprise sets {b_(f)^((i))} and {c_(d) ^((i))} for each SD basis vector a_(i), where {b_(f)^((i))} and {c_(d) ^((i))} are vectors from a joint set of FD and DDbasis vector pairs {(b_(f) ^((i)),c_(d) ^((i)))}.

In one embodiment, one of the sets of basis vectors is set to anidentity matrix.

In one embodiment, the first set of SD basis vectors comprises eitherDFT vectors or port selection vectors, the second set of FD basisvectors comprises DFT vectors, and the third set of DD basis vectorscomprises DFT vectors.

FIG. 17 illustrates a flow chart of another method 1700, as may beperformed by a base station (BS) such as BS 102, according toembodiments of the present disclosure. The embodiment of the method 1700illustrated in FIG. 17 is for illustration only. FIG. 17 does not limitthe scope of this disclosure to any particular implementation.

As illustrated in FIG. 17 , the method 1700 begins at step 1702. In step1702, the BS (e.g., 101-103 as illustrated in FIG. 1 ), generates aconfiguration about a channel state information (CSI) report, theconfiguration including information about a codebook, the codebookcomprising components: (i) sets of basis vectors including a first setof vectors each of length P_(CSIRS)×1 for a SD, a second set of vectorseach of length N₃×1 for a FD, and a third set of vectors each of lengthN₄×1 for a DD, and (ii) coefficients associated with each basis vectortriple (a_(i),b_(f),c_(d)), a_(i) from the first set, b_(f) from thesecond set, and c_(d) from the third set.

In step 1704, the BS transmits the configuration.

In step 1706, the BS receives the CSI report based on the configuration,wherein the CSI report includes: at least one basis vector indicatorindicating all or a portion of the sets of basis vectors, and at leastone coefficient indicator indicating all or a portion of thecoefficients, wherein N₃ and N₄ are total number of FD and DD unitsrespectively, and wherein P_(CSIRS) is a number of CSI-RS portsconfigured for the CSI report.

In one embodiment, for each FD unit among the total of N₃ FD units andfor each DD unit among the total of N₄ DD units, a precoding vector oflength P_(CSIRS)×1 for a layer l E {1, . . . , v} is based on: a firstsum over the first set of SD basis vectors, a second sum over the secondset of FD vectors, and a third sum over the third set DD vectors, wherethe precoding vector is given by:

${W^{l} = {\frac{1}{\sqrt{\gamma}}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{v} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,i,f,d}}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{v} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,{i + L},f,d}}}}}}\end{bmatrix}}},$

wherein:

L is a number of basis vectors in the first set,

M_(v) is a number of basis vectors in the second set,

N is a number of basis vectors in the third set,

v_(m) ₁ _((i)) _(,m) ₂ _((i)) is a vector of length

$\frac{P_{CSIRS}}{2} \times 1{{and}\begin{bmatrix}v_{m_{1}^{(i)},m_{2}^{(i)}} \\v_{m_{1}^{(i)},m_{2}^{(i)}}\end{bmatrix}}$

is an i-th SD basis vector in the first set,

y_((t,l) ^((i,f)) is a t-th element of an f-th FD basis vector of lengthN₃×1 in the second set,

ϕ_(u,l) ^((i,d)) is a u-th element of a d-th DD basis vector of lengthN₄×1 in the third set,

γ is a normalization factor, and

v is a number of layers.

In one embodiment, the first and the second sets of basis vectors for SDand FD respectively are independent, and the third set of basis vectorscomprises a set of DD basis vectors {c_(d) ^((i,f))} for each (SD, FD)basis vector pair (a_(i),b_(f)).

In one embodiment, the first and the second sets of basis vectors for SDand FD respectively are independent, and the third set of basis vectorscomprises a set of DD basis vectors {c_(d) ^((i))} for each SD basisvector a_(i).

In one embodiment, the first set of basis vectors for SD is independent,the second set of basis vectors comprises a set of FD basis vectors{b_(f) ^((i))} for each SD basis vector a_(i), and the third set ofbasis vectors comprises a set of DD basis vectors {c_(d) ^((i))} foreach SD basis vector a_(i).

In one embodiment, the first set of basis vectors for SD is independent,and the second and the third sets of basis vectors comprise sets {b_(f)^((i))} and {c_(d) ^((i))} for each SD basis vector a_(i), where {b_(f)^((i))} and {c_(d) ^((i))} are vectors from a joint set of FD and DDbasis vector pairs {(b_(f) ^((i)),c_(d) ^((i)))}.

In one embodiment, one of the sets of basis vectors is set to anidentity matrix.

In one embodiment, the first set of SD basis vectors comprises eitherDFT vectors or port selection vectors, the second set of FD basisvectors comprises DFT vectors, and the third set of DD basis vectorscomprises DFT vectors.

The above flowcharts illustrate example methods that can be implementedin accordance with the principles of the present disclosure and variouschanges could be made to the methods illustrated in the flowchartsherein. For example, while shown as a series of steps, various steps ineach figure could overlap, occur in parallel, occur in a differentorder, or occur multiple times. In another example, steps may be omittedor replaced by other steps.

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims. None of the description in this application should be read asimplying that any particular element, step, or function is an essentialelement that must be included in the claims scope. The scope of patentedsubject matter is defined by the claims.

What is claimed is:
 1. A user equipment (UE), the UE comprising: atransceiver configured to: receive a configuration about a channel stateinformation (CSI) report, the configuration including information abouta codebook, the codebook comprising components: (i) sets of basisvectors including a first set of vectors each of length P_(CSIRS)×1 fora spatial domain (SD), a second set of vectors each of length N₃×1 for afrequency domain (FD), and a third set of vectors each of length N₄×1for a Doppler domain (DD), and (ii) coefficients associated with eachbasis vector triple (a_(i),b_(f),c_(d)), a_(i) from the first set, b_(f)from the second set, and c_(d) from the third set; and a processoroperably coupled to the transceiver, the processor configured to:determine, based on the configuration, the components; and wherein: thetransceiver is further configured to transmit the CSI report including:at least one basis vector indicator indicating all or a portion of thesets of basis vectors, and at least one coefficient indicator indicatingall or a portion of the coefficients, N₃ and N₄ are total number of FDand DD units respectively, and P_(CSIRS) is a number of CSI-RS portsconfigured for the CSI report.
 2. The UE of claim 1, wherein for each FDunit among the total of N₃ FD units and for each DD unit among the totalof N₄ DD units, a precoding vector of length P_(CSIRS)×1 for a layerl∈{1, . . . , v} is based on: a first sum over the first set of SD basisvectors, a second sum over the second set of FD vectors, and a third sumover the third set DD vectors, where the precoding vector is given by:${W^{l} = {\frac{1}{\sqrt{\gamma}}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{v} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,i,f,d}}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{v} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,{i + L},f,d}}}}}}\end{bmatrix}}},$ wherein: L is a number of basis vectors in the firstset, M_(v) is a number of basis vectors in the second set, N is a numberof basis vectors in the third set, v_(m) ₁ _((i)) _(,m) ₂ _((i)) is avector of length $\frac{P_{CSIRS}}{2} \times 1{{and}\begin{bmatrix}v_{m_{1}^{(i)},m_{2}^{(i)}} \\v_{m_{1}^{(i)},m_{2}^{(i)}}\end{bmatrix}}$  is an i-th SD basis vector in the first set, y_(t,l)^((i,f)) is a t-th element of an f-th FD basis vector of length N₃×1 inthe second set, ϕ_(u,l) ^((i,d)) is a u-th element of a d-th DD basisvector of length N₄×1 in the third set, γ is a normalization factor, andv is a number of layers.
 3. The UE of claim 1, wherein the first and thesecond sets of basis vectors for SD and FD respectively are independent,and the third set of basis vectors comprises a set of DD basis vectors{c_(d) ^((i,f))} for each (SD, FD) basis vector pair (a_(i),b_(f)). 4.The UE of claim 1, wherein the first and the second sets of basisvectors for SD and FD respectively are independent, and the third set ofbasis vectors comprises a set of DD basis vectors {c_(d) ^((i))} foreach SD basis vector a_(i).
 5. The UE of claim 1, wherein: the first setof basis vectors for SD is independent, the second set of basis vectorscomprises a set of FD basis vectors {b_(f) ^((i))} for each SD basisvector a_(i), and the third set of basis vectors comprises a set of DDbasis vectors {c_(d) ^((i))} for each SD basis vector a_(i).
 6. The UEof claim 1, wherein: the first set of basis vectors for SD isindependent, and the second and the third sets of basis vectors comprisesets {b_(f) ^((i))} and {c_(d) ^((i))} for each SD basis vector a_(i),where {b_(f) ^((i))} and {c_(d) ^((i))} are vectors from a joint set ofFD and DD basis vector pairs {(b_(f) ^((i)),c_(d) ^((i))}.
 7. The UE ofclaim 1, wherein one of the sets of basis vectors is set to an identitymatrix.
 8. The UE of claim 1, wherein the first set of SD basis vectorscomprises either DFT vectors or port selection vectors, the second setof FD basis vectors comprises DFT vectors, and the third set of DD basisvectors comprises DFT vectors.
 9. A base station (BS) comprising: aprocessor configured to generate a configuration about a channel stateinformation (CSI) report, the configuration including information abouta codebook, the codebook comprising components: (i) sets of basisvectors including a first set of vectors each of length P_(CSIRS)×1 fora spatial domain (SD), a second set of vectors each of length N₃×1 for afrequency domain (FD), and a third set of vectors each of length N₄×1for a Doppler domain (DD), and (ii) coefficients associated with eachbasis vector triple (a_(i),b_(f),c_(d)), a_(i) from the first set, b_(f)from the second set, and c_(d) from the third set; and a transceiveroperably coupled to the processor, the transceiver configured to:transmit the configuration; and receive the CSI report based on theconfiguration, wherein the CSI report includes: at least one basisvector indicator indicating all or a portion of the sets of basisvectors, and at least one coefficient indicator indicating all or aportion of the coefficients, wherein N₃ and N₄ are total number of FDand DD units respectively, and wherein P_(CSIRS) is a number of CSI-RSports configured for the CSI report.
 10. The BS of claim 9, wherein foreach FD unit among the total of N₃ FD units and for each DD unit amongthe total of N₄ DD units, a precoding vector of length P_(CSIRS)×1 for alayer l∈{1, . . . , v} is based on: a first sum over the first set of SDbasis vectors, a second sum over the second set of FD vectors, and athird sum over the third set DD vectors, where the precoding vector isgiven by: ${W^{l} = {\frac{1}{\sqrt{\gamma}}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{v} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,i,f,d}}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{v} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,{i + L},f,d}}}}}}\end{bmatrix}}},$ wherein: L is a number of basis vectors in the firstset, M_(v) is a number of basis vectors in the second set, N is a numberof basis vectors in the third set, v_(m) ₁ _((i)) _(,m) ₂ _((i)) is avector of length $\frac{P_{CSIRS}}{2} \times 1{{and}\begin{bmatrix}v_{m_{1}^{(i)},m_{2}^{(i)}} \\v_{m_{1}^{(i)},m_{2}^{(i)}}\end{bmatrix}}$  is an i-th SD basis vector in the first set, y_(t,l)^((i,f)) is a t-th element of an f-th FD basis vector of length N₃×1 inthe second set, ϕ_(u,l) ^((i,d)) is a u-th element of a d-th DD basisvector of length N₄×1 in the third set, γ is a normalization factor, andv is a number of layers.
 11. The BS of claim 9, wherein the first andthe second sets of basis vectors for SD and FD respectively areindependent, and the third set of basis vectors comprises a set of DDbasis vectors {c_(d) ^((i,f))} for each (SD, FD) basis vector pair(a_(i),b_(f)).
 12. The BS of claim 9, wherein the first and the secondsets of basis vectors for SD and FD respectively are independent, andthe third set of basis vectors comprises a set of DD basis vectors{c_(d) ^((i))} for each SD basis vector a_(i).
 13. The BS of claim 9,wherein: the first set of basis vectors for SD is independent, thesecond set of basis vectors comprises a set of FD basis vectors {b_(f)^((i))} for each SD basis vector a_(i), and the third set of basisvectors comprises a set of DD basis vectors {c_(d) ^((i))} for each SDbasis vector a_(i).
 14. The BS of claim 9, wherein: the first set ofbasis vectors for SD is independent, and the second and the third setsof basis vectors comprise sets {b_(f) ^((i))} and {c_(d) ^((i))} foreach SD basis vector a_(i), where {b_(f) ^((i))} and {c_(d) ^((i))} arevectors from a joint set of FD and DD basis vector pairs {(b_(f)^((i)),c_(d) ^((i)))}.
 15. The BS of claim 9, wherein one of the sets ofbasis vectors is set to an identity matrix.
 16. The BS of claim 9,wherein the first set of SD basis vectors comprises either DFT vectorsor port selection vectors, the second set of FD basis vectors comprisesDFT vectors, and the third set of DD basis vectors comprises DFTvectors.
 17. A method for operating a user equipment (UE), the methodcomprising: receiving a configuration about a channel state information(CSI) report, the configuration including information about a codebook,the codebook comprising components: (i) sets of basis vectors includinga first set of vectors each of length P_(CSIRS)×1 for a spatial domain(SD), a second set of vectors each of length N₃×1 for a frequency domain(FD), and a third set of vectors each of length N₄×1 for a Dopplerdomain (DD), and (ii) coefficients associated with each basis vectortriple (a_(i),b_(f),c_(d)), a_(i) from the first set, b_(f) from thesecond set, and c_(d) from the third set; determining, based on theconfiguration, the components; and transmitting the CSI reportincluding: at least one basis vector indicator indicating all or aportion of the sets of basis vectors, and at least one coefficientindicator indicating all or a portion of the coefficients, wherein N₃and N₄ are total number of FD and DD units respectively, and whereinP_(CSIRS) is a number of CSI-RS ports configured for the CSI report. 18.The method of claim 17, wherein for each FD unit among the total of N₃FD units and for each DD unit among the total of N₄ DD units, aprecoding vector of length P_(CSIRS)×1 for a layer l∈{1, . . . , v} isbased on: a first sum over the first set of SD basis vectors, a secondsum over the second set of FD vectors, and a third sum over the thirdset DD vectors, where the precoding vector is given by:${W^{l} = {\frac{1}{\sqrt{\gamma}}\begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{v} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,i,f,d}}}}}} \\{\sum\limits_{i = 0}^{L - 1}{v_{m_{1}^{(i)},m_{2}^{(i)}}{\sum\limits_{f = 0}^{M_{v} - 1}{\sum\limits_{d = 0}^{N - 1}{y_{t,l}^{({i,f})}\phi_{u,l}^{({i,d})}x_{l,{i + L},f,d}}}}}}\end{bmatrix}}},$ wherein: L is a number of basis vectors in the firstset, M_(c) is a number of basis vectors in the second set, N is a numberof basis vectors in the third set, v_(m) ₁ _((i)) _(,m) ₂ _((i)) is avector of $\frac{P_{CSIRS}}{2} \times 1{{and}\begin{bmatrix}v_{m_{1}^{(i)},m_{2}^{(i)}} \\v_{m_{1}^{(i)},m_{2}^{(i)}}\end{bmatrix}}$  is an i-th SD basis vector in the first set, y_(t,l)^((i,f)) is a t-th element of an f-th FD basis vector of length N₃×1 inthe second set, ϕ_(u,l) ^((i,d)) is a u-th element of a d-th DD basisvector of length N₄×1 in the third set, γ is a normalization factor, andv is a number of layers.
 19. The method of claim 17, wherein the firstand the second sets of basis vectors for SD and FD respectively areindependent, and the third set of basis vectors comprises a set of DDbasis vectors {c_(d) ^((i,f))} for each (SD, FD) basis vector pair(a_(i),b_(f)).
 20. The method of claim 17, wherein the first and thesecond sets of basis vectors for SD and FD respectively are independent,and the third set of basis vectors comprises a set of DD basis vectors{c_(d) ^((i))} for each SD basis vector a_(i).